Math Word Problems Demystified - A Self Teaching Guide

101 x

101

¼

40

10

x¼ 4

Findy:

2 xþy¼ 13

2 ð 4 Þþy¼ 13

8 þy¼ 13

8 
 8 þy¼ 13 
 8

y¼ 5

4. Substitute forxin the second equation and findysincex¼ 2 y.
   3 xþ 4 y¼ 40

3 ð 2 yÞþ 4 y¼ 40

6 yþ 4 y¼ 40

10 y¼ 40

101 y

101

¼

40

10

y¼ 4

Findx:

x¼ 2 y

x¼ 2 ð 4 Þ

x¼ 8

5. Substitute foryin the first equation sincey¼
   xþ 2
   2 x
   y¼
   11

2 x
ð
xþ 2 Þ¼
 11

2 xþx
 2 ¼
 11

3 x
 2 ¼
 11

REFRESHER V Systems of Equations 205