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
xþyy¼ 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