帮忙解1道题 （若9的m次方等于12，27的n次方等于15，求3的4m次方-6n次方的值？）

9^m=12,
3^(2m)=12

27^n=15,
3^(3n)=15

3^(4m-6n)=(3^4m)/(3^6n)=[3^2m]^2/[3^3n]^2=12^2/15^2=16/25

9^m=12 => 3^2m=12
3^4m=(3^2m)^2=12*12=144;

27^n=15 => 3^3n=15
3^6n=(3^3n)^2=15*15=225;

3^（4m-6n）＝3^4m / 3^6n =144/225

9^m=3^2m=12
27^n=3^3n=15

3^(4m-6n)=3^4m÷3^6n=(3^2m)^2÷(3^3n)^2=(12^2)÷(15^2)=144/225

144/225