a^(m+1)b^(n+2)*a^(2n-1)*b=a^5b^4
a^(m+1+2n-1)b^(n+2+1)=a^5b^4
a^(m+2n)b^(n+3)=a^5b^4
n+3=4
n=1
m+2n=5
m+2=5
m=3
m+n=3+1=4