1. Word Problems
Section 6.4

2. Some problems expect you to know certain information before you begin.
These facts often deals with geometry, measurements, or money.

3. Example 1:
The length of a rectangle is 3 more than twice the width. The perimeter is 66 cm. Find the dimensions.
What does this problem expect you to know?
How to find the perimeter of a rectangle.

4. Example 1:
The length of a rectangle is 3 more than twice the width. The perimeter is 66 cm. Find the dimensions.
Defining the Variables:
What are you trying to find in this problem?
What are the unknowns?
Length of rectangle
Width of rectangle L W

5. Example 1:
The length of a rectangle is 3 more than twice the width. The perimeter is 66 cm. Find the dimensions.
Creating Equations:
What do we already know?
The length is 3 more than width
L = 3 + W
The Perimeter is 66cm
2L + 2W = 66

6. Example 1:
The length of a rectangle is 3 more than twice the width. The perimeter is 66 cm. Find the dimensions.
Solve: Substitution
L = 3 + W
2L + 2W = 66
2(3 + W) + 2W = 66
6 + 2W + 2W = 66
6 + 4W = 66
4W = 60
W = 15

7. Example 2: What do we know?
Two angles are supplementary and the larger angle is 30 more than twice the smaller. What are the angles?
What do they expect us to know?
Supplementary angles are two angles that add to (They make a straight line.)

8. Example 2: Define Variables
Two angles are supplementary and the larger angle is 30 more than twice the smaller. What are the angles?
What is unknown?
The value of the two angles.
We could call them x and y, or a and b. Any pair of letters will work.

9. Example 2: Create Equations
Two angles are supplementary and the larger angle is 30 more than twice the smaller. What are the angles?
What do we know?
They add to 180 (supplemental angles)
x + y = 180
One angle is 30 more than twice the other.
x = y
“twice” means 2 times/multiplied by
“is” implies equal to =
“more” usually means add/plus.

10. Example 2: Solve the System
Two angles are supplementary and the larger angle is 30 more than twice the smaller. What are the angles?
x + y = 180
x = y
(30 + 2y) + y = 180
30 + 3y = 180
3y = 150
y = 50
If x = y,
and y = 50, then:
x = (50)
x =
x = 130

11. In your notebooks: Solve the following: (Hint: Elimination will probably work best)
At a convenience store, Luis bought 3 candy bars and 2 sodas for $ Savannah bought 2 candy bars and 3 sodas for $ How much does each item cost?

12. Make a poster: In groups of 2 or 3, solve your word problem
(you want to use scratch paper first.)
Paper and markers are in the back.
Your posters should be creative, not crude.
On your poster you must have defined variables, two equations created from the word problem, and a system solved using one of the three methods.
You will be presenting your posters in front of the class.
You will be graded on accuracy, creativity, explanation (during presentation and on the poster), and neatness.

13. Homework: pg 287-288 (6-16 evens, 32-35 all)