1) 9b+6b-15=615
9b+6b=615+15
15b=630
b=630/15
b=42
2) 2a+123a+97=472
125a=472-97
125a=375
a=375/125
a=3
3)17x-x+5x-19=170
21x=170+19
21x=189
x=189/21
x=9
4)17y-y-22y+40=190
-6y=190-40
-6y=150
y=150/(-6)
y=-25
