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6 th Grade Primary Mathematics October 23, 2012. Algebraic Expressions Algebraic expression can be used to describe an existing relationship. Amelia was.

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Presentation on theme: "6 th Grade Primary Mathematics October 23, 2012. Algebraic Expressions Algebraic expression can be used to describe an existing relationship. Amelia was."— Presentation transcript:

1 6 th Grade Primary Mathematics October 23, 2012

2 Algebraic Expressions Algebraic expression can be used to describe an existing relationship. Amelia was born when her mother was 25 years old. Amelia’s Age Mother’s Age 25 years

3 Amelia’s Age Mother’s Age 25 years Will Amelia’s mother always be 25 years older than Amelia? Amelia's AgeHer mother’s age = = = = = 27 XX + 25 X

4 John takes all of his dollar bills to the bank to exchange them for quarters. How many quarters will he receive? Number of Dollars Number of Quarters 11 x 4 = 4 22 x 4 = 8 55 x 4 = x 4 = x 4 = 400 DD x 4 = 4D

5 Graphs of Functions Sally’s allowance is $5 per week. Her parents give her an additional $1 for each chore that she does. Number of Chores Sally’s allowance = = = = 12 x 5 + x Number of Chores Sally’s Allowance ($)

6 Primary Mathematics Textbook 6A page 26 Ellen’s Age Dylan’s Age = = 5 x x + 3 Ellen’s Age (years) Dylan’s Age (years) How old will Ellen be when Dylan is 10? How old will Dylan be when Ellen is 10? = 13 7

7 Joel has three more rabbits than turtles. (a)If Joel has T turtles, how many rabbits does he have? (b)If Joel has R rabbits, how many turtles does he have? Number of Rabbits Number of Turtles 3T T + 3 R R - 3 Writing Expressions

8 There are four times as many boys on the track team as girls. (a)If there are G girls on the track team, how many boys are on the team? (b)If there are B boys on the tract team, how many girls are on the team? (c)If there are X number of athletes on the track team, how many are girls and how many are boys? Number of Girls Number of Boys G 4 x G

9 There are four times as many boys on the track team as girls. (a)If there are G girls on the track team, how many boys are on the team? (b)If there are B boys on the tract team, how many girls are on the team? (c)If there are X number of athletes on the track team, how many are girls and how many are boys? Number of Girls Number of Boys B B ÷ 4

10 There are four times as many boys on the track team as girls. (a)If there are G girls on the track team, how many boys are on the team? (b)If there are B boys on the tract team, how many girls are on the team? (c)If there are X number of athletes on the track team, how many are girls and how many are boys? Number of Girls Number of Boys X

11 Equations An equation is a mathematical statement of equality between algebraic expressions.

12 There are four times as many boys on the track team as girls. If there are 30 athletes on the team, how many girls and boys are there? Number of Girls Number of Boys 30 X 4X x + 4x = 30 5x = 30 x = There are 6 girls and 24 boys on the team.

13 Joel has three more rabbits than turtles. If he has 7 animals in all, how many rabbits does he have? Number of Rabbits Number of Turtles 3 7 Method 1 y y + 3 y y = 7 2y + 3 = 7 2y = 4 y = = 5 Joel had 2 turtles and 5 rabbits.

14 Joel has three more rabbits than turtles. If he has 7 animals in all, how many rabbits does he have? Number of Rabbits Number of Turtles 3 7 Method 2 w w - 3 w + w – 3 = 7 2w – 3 = 7 2w = 10 w = – 3 = 2 Joel had 2 turtles and 5 rabbits.

15 Morris spent $ on CD’s and Video Games. If he spent $87.95 on Video Games, how much did Morris spend out CD’s? $ $87.95 x CD’s Video Games x = x = Morris spent $27.75 on CD’s.

16 Use the graph to solve for y 12

17 Use the graph to solve for x 6 12

18 Algebraic Expressions II There are x pens in a box and y pencils in a box. If Mrs. Smith purchased 5 boxes of pens and 3 boxes of pencils, how many writing implements did she buy? Pens Pencils x y xxxx yy Number of Pens = 5x Number of Pencils = 3y Mrs. Smith bought 5x + 3y writing implements in all.

19 There are 8 pens in a box and 10 pencils in a box. If Mrs. Smith purchased s boxes of pens and t boxes of pencils, how many writing implements did she buy? Pens Pencils s t Number of pens = 8s Number of pencils = 10t Mrs. Smith purchased 8s + 10t writing implements in all.

20 At a farm, Ben and Kathy were each given a bucket that weighed x grams. Ben picked y grams of blueberries. The blueberries Kathy picked were three times as heavy as Ben’s. Ben Kathy xy yyy x

21 At a farm, Ben and Kathy were each given a bucket that weighed x grams. Ben picked y grams of blueberries. The blueberries Kathy picked were three times as heavy as Ben’s. What is the total weight of both buckets? Ben Kathy xy yyy x ? The total weight of both buckets is 2x + 4y

22 At a farm, Ben and Kathy were each given a bucket that weighed x grams. Ben picked y grams of blueberries. The blueberries Kathy picked were three times as heavy as Ben’s. How much more does Kathy’s bucket weight than Ben’s bucket? Ben Kathy xy yyy x ? Kathy’s bucket weighs 2y more grams than Ben’s

23 Darryl has $7700 in his investment account after a year. He earned 10% of it as interest. How much did he have in his account at first? $7700 Darryl’s money after a year Amount Darryl had at first 10% of the original amount 11 units = $ unit = $ units = $7000 Darryl had $7000 in his account at first. Primary Mathematics Workbook 6A page 73

24 Mr. Arasim sold a bed frame for $625. The selling price was 25% more than the cost price. What is the cost price of the bed frame? Selling price of the bed frame $625 Cost price of the bed frame 25% of the cost price 5 units = $625 1 unit = $125 4 units = $500 The cost price of the bed frame is $500. Primary Mathematics Workbook 6A page 74

25 Primary Mathematics Textbook 6A page 77 Problem 3 100% 15% 40% ? ? = 100 – 15 – 40 ? = 45 45%

26 Primary Mathematics Textbook 6A page 77 Problem seats 15% 40% 100% = 4000 tickets 10% = 400 tickets 5% = 200 tickets 40% = 4(10%) = 4(400)= % $120$80 ? 45% = 1800 tickets 1800 tickets are priced at $50

27 The figure is made up of two rectangles. Find the area of the figure. 30 feet 20 feet 8 feet 10 feet Area = 20 x 20 Area = 400 square feet Area = 10 x 8 Area = 80 square feet The area of the figure is 480 square feet. Area = PM 4A

28 The figure is made up of two rectangles. Find the area of the figure. 30 feet 20 feet 8 feet 12 feet Area = 30 x 8 Area = 240 square feet Area = 20 x 12 Area = 240 square feet Area = Area= 480 square feet PM 4A

29 Primary Mathematics Textbook 6A page 95. Number of pens Number of pencils The ratio of pens to pencils is 3 : 2

30 Primary Mathematics Textbook 6A page 137. $ $27 Cost of mileage Cost of mileage = – 3 (27) =

31 Primary Mathematics Textbook 6A page 137. $ $27 $ x = 621 miles

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