1) 9b+6b-15=615
2) 17x-x+5x-19=170
1)b=42
2)x=9
1)15b-15=615
15b=615+15
15b=630
b=630/15=42
2)17x-x+5x-19=170
21x-19=170
21x=170+19
21x=189
x=189/21=9