a*(x^3y^4)^3/[1/6x^(2+n)y^4]=3/4x^2y^2m,
6a*(x^9y^12)/[x^(2+n)y^4]=3/4x^2y^2m,
6a* x^(9-2-n)y^(12-4)=3/4x^2y^2m,
6a* x^(7-n)y^8=3/4x^2y^2m,
∴6a=3/4,7-n=2,8=2m
∴a=1/8,m=4,n=5