(1)10^m=40 10^n=0.2
则 10^(2n)=0.2^2
10^m/10^(2n)=10^(m-2n)=40/0.04=10^3
则m-2n=3
(2)3^m/9^n=3^m/3^2n=3^(m-2n)=3^3=27