9b+6b-15 = 615,2a+123a +97,17x-x+5x-19 = 170,73y-y+19 = 227

1)15b=630           
b=42
2)125a+97
3)21x=170
x=8 2/21
4)72y=208
y=2 8/9

9b+6b-15=615
15b-15=615
15b=615+15
15b=630
b=42