2的m次方=a,8的n次方=b
则2的m次方=a,2的3n次方=b
4的2m-3n+3次方
=2的4m-6n+6次方
=(2的m次方)的4次方÷（2的3n次方）的2次方×2的6次方
=a的4次方÷b²×64
=64a的4次方/b²