(a^n*b^m*b)^3=a^9b^15
(a^n*b^m*b)^3=(a^3b^5)^3
a^n*b^m*b=a^3b^5
a^n*b^(m+1)=a^3b^5
n=3
m+1=5
m=4
2^(m+n)
=2^(3+4)
=2^7
=128