1. Do Now
Solve.
1. x – 17 = 32
2. y + 11 = 41
3. = 18
4. 12x = 108
5. x – 9 = 20
x = 49
y = 30 w 5
w = 90
x = 9
x = 29
Hwk: p29 odd, Test this Friday on chap 3 sec 1-6.

2. EQ: How do I solve one-step equations that contain decimals?
M7A2.a Given a problem, define a variable, write an equation, solve the equation, and interpret the solution;
M7A2.b Use the addition and multiplication properties of equality to solve one- and two-step linear equations;
M7N1.c Add, subtract, multiply, and divide positive and negative rational numbers; M7N1.d Solve problems using
rational numbers

3. Students in a physical education class were running
40-yard dashes as part of a fitness test. The slowest time in the class was 3.84 seconds slower than the fastest time of 7.2 seconds.
You can write an equation to represent this situation.
The slowest time s minus 3.84 is equal to the fastest
time of 7.2 seconds.
s – 3.84 = 7.2

4. Additional Example 1: Solving Equations by Adding and Subtracting
Solve.
A. n – 2.75 = 8.3
n – 2.75 = 8.30
+ 2.75
+ 2.75
Add to isolate n.
n = 11.05
B. a = 42
a = 42.00
–32.66
–32.66
Subtract to isolate a. a =
9.34

5. Check It Out: Example 1
Solve.
A. n – 1.46 = 4.7
n – 1.46 = 4.70
+ 1.46
+ 1.46
Add to isolate n.
n = 6.16
B. a = 36
a = 36.00
–27.51
–27.51
Subtract to isolate a. a =
8.49

6. Additional Example 2A: Solving Equations by Multiplying and Dividing
Solve. x
= 5.4
4.8 x =
5.4
4.8 x
4.8 =
5.4
· 4.8
Multiply to isolate x.
4.8
x = 25.92

7. Additional Example 2B: Solving Equations by Multiplying and Dividing
Solve.
9 = 3.6d
9 = 3.6d 9
3.6d =
Divide to isolate d.
3.6
3.6 9 = d
Think: 9 ÷ 3.6 = 90 ÷ 36
3.6
2.5 = d

8. · · 3.5 Check It Out: Example 2A Solve. x = 2.4 3.5 x = 2.4 3.5 x 3.5
Multiply to isolate x.
3.5
x = 8.4

9. Check It Out: Example 2B
Solve.
9 = 2.5d
9 = 2.5d 9
2.5d =
Divide to isolate d.
2.5
2.5 9 = d
Think: 9 ÷ 2.5 = 90 ÷ 25
2.5
3.6 = d

10. A board-game box is 2. 5 inches tall
A board-game box is 2.5 inches tall. A toy store has shelving measuring 15 inches vertically in which to store the boxes. How many boxes can be stacked in the space?
List the important information:
• Each board-game box is 2.5 inches tall.
• The store has shelving space measuring 15 inches.
The total height of the boxes is equal to the height of one box times the number of boxes. Since you know how tall the shelf is you can write an equation with b being the number of boxes.
2.5b = 15

11. Additional Example 3 Continued
2.5b = 15
2.5b = 15
2.5
2.5
b = 6
Six boxes can be stacked in the space.

12. A canned good is 4. 5 inches tall
A canned good is 4.5 inches tall. A grocery store has shelving measuring 18 inches vertically in which to store the cans. How many cans can be stacked in the space?
List the important information:
4.5c = 18

13. Check It Out: Example 3 Continued
Solve
4.5c = 18
4.5c = 18
4.5
4.5
c = 4
Four cans can be stacked in the space.

14. You try on your paper, put name on paper
Solve.
1. x – = 19.5
c = –103.32 3.
4. m =–14.35
5. The French Club is selling coupon books for $8.25 each. How many books must be sold to bring in $5,940?
x = 33.73
c = –8.2 x
= 6.1
x = 56.73
9.3
m = –27.32
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