Math Word Problems Demystified - A Self Teaching Guide

Substitute forxin the second equation and solve fory.

4 yþ 10 ¼ 2 yþ 20

4 y
 2 yþ 10 ¼ 2 y
 2 yþ 20

2 yþ 10 ¼ 20

2 yþ 10 
 10 ¼ 20 
 10

2 y¼ 10

21 y

21

¼

10

2

y¼ 5

Solve forx:

x¼ 4 y

x¼ 4  5

x¼ 20

Matt is 20 and Mike is 5 years old.

5. Letx¼the number of bags of $0.50 candy
   andy¼the number of bags of $0.75 candy

xþy¼ 40

50 xþ 75 y¼ 2325

Solve foryin the first equation.

x
xþy¼ 40 
x

y¼ 40 
x

224 LESSON 18 Using Two Equations