Math Word Problems Demystified - A Self Teaching Guide

Solve foryin the first equation.

x
xþy¼ 18 
x

y¼ 18 
x

Substitute in the second equation and solve forx.

5 xþ 10 ð 18 
xÞ¼ 130

5 xþ 180 
 10 x¼ 130

 5 xþ 180 ¼ 130

 5 xþ 180 
 180 ¼ 130 
 180

 5 x¼
 50

 51 x


 5

¼

50

5

x¼10 nickels

Solve fory:

xþy¼ 18

10 þy¼ 18

10 
 10 þy¼ 18 
 10

y¼8 dimes

4. Letx¼Matt’s age
   andy¼Mike’s age

x¼ 4 y

xþ 10 ¼ 2 ðyþ 10 Þ

LESSON 18 Using Two Equations 223