Solve foryin the first equation.
xxþy¼ 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
- Letx¼Matt’s age
andy¼Mike’s age
x¼ 4 y
xþ 10 ¼ 2 ðyþ 10 Þ
LESSON 18 Using Two Equations 223