a+b=65a

Question

a=b-9

Answer 1

since a = b-9, use that and you have
b-9+b = 65(b-9)
2b-9 = 65b-585
63b = 576
b = 576/63

Something tells me you meant
a+b = 65
In that case,
b-9+b = 65
b = 37