`Think`

What operations are

used in th e equation?

The e q u a tio n uses

multiplication and

a d d itio n. You can undo

the addition first, and

then the m ultiplication.

Think

How can a model

help you w rite the

equation?

The m odel show s th a t

a h a lf o f a sheet per ad

plus 5 sheets fo r th e

title banner is equal to

18 sheets.

I- 1 8................. 1

`Solving a Two-Step Equation`

What is the solution of 2x + 3 = 15?

2x + 3 = 15

Subtract 3 from each side.

Simplify.

Divide each side by 2.

Simplify.

`2x + 3 - 3 = 15`

2x = 12

2 x

2

`12`

2

x = 6

Check 2x + 3 = 15

2(6) + 3 = 15

15 = 15

`Substitute 6 for x.`

Simplify. The solution checks.

`^ Got It? 1.W hat is th e solution of 5 = ; 3?`

`Problem 2 Using an Equation as a M odel`

`Community Service You are making a bulletin board to advertise community`

service opportunities in your town. You plan to use half a sheet of construction

paper for each ad. You need 5 sheets of construction paper for a title banner.

You have 18 sheets of construction paper. How many ads can you make?

- Paper per ad: j sheet
- Paper for banner: 5 sheets
- Total paper: 18 sheets

`Need`

The num ber o f ads

you can make

`F*`

W rite and solve an e q u a tio n. Let th e

variable represent the unknown.

`Let a = th e n u m b e r of ads you can make.`

\a + 5 = 18

\a + 5 - 5 = 18

= 13

`Subtract 5 from each side.`

Simplify.

`Multiply each side by 2.`

Simplify.

You can m ake 26 com m unity service advertisem ents for the bulletin board.

`2 L a 2(13)`

a = 26

`G ot It? 2. Suppose you u sed o n e q u a rte r of a sh eet of p a p e r for each ad an d`

four full sheets for th e title b a n n e r in Problem 2. How m any ads

could you make?

}

c

`PowerAlgebra.com`

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Lesson 2-2 So l v i n g Tw o - St e p Eq u a t i o n s -