Math Word Problems Demystified - A Self Teaching Guide

Since the total interest is $245, the second equation is

4%xþ 6

1

2

%y¼ 245

IMPLEMENTATION: Solve the system

xþy¼ 5000

4%xþ 6

1

2

%y¼ 245

Solve the first equation forx. Substitute in the second equation and

solve fory.

xþy¼ 5000

xþy
y¼ 5000 
y

x¼ 5000 
y

Then

0 : 04 xþ 0 : 065 y¼ 245

0 : 04 ð 5000 
yÞþ 0 : 065 y¼ 245

200 
 0 : 04 yþ 0 : 065 y¼ 245

200 þ 0 : 025 y¼ 245

200 
 200 þ 0 : 025 y¼ 245 
 200

0 : 025 y¼ 45

0 : 0251 x

0 : 025

¼

45

0 : 025

y¼ 1800

LESSON 18 Using Two Equations 219