a)
\frac{5^{12}}{5^7*5}=\frac{5^{12}}{5^8}=5^{12-8}=5^4
b)
(\frac{1}{3})^4*6^4=(\frac{1}{3}*6)^4=2^4
c)
(\frac{8}{5})^3*(\frac{5}{4})^3=(\frac{8}{5}*\frac{5}{4})^3=2^3
d)
(\frac{36}{7})^2*(\frac{7}{9})^2=(\frac{36}{7}*\frac{7}{9})^2=4^2
e)
\frac{32^3}{16^3}=(\frac{32}{16})^3=2^3
f)
\frac{6^3}{18^3}=(\frac{6}{18})^3=(\frac{1}{3})^3
g)
42^2:6^2=(42:6)^2=7^2
h)
5^4:15^4=(\frac{5}{15})^4=(\frac{1}{3})^4