Lời giải:
a) $8^3:(-8)^{-5}=8^3:(-8^{-5})=-(8^3:8^{-5})$
$=-8^{3-(-5)}=-8^{13}$
b) $(\frac{-5}{16})^{12}:(\frac{5}{-16})^4$
$=(\frac{-5}{16})^{12}:(\frac{-5}{16})^4$
$=(\frac{-5}{16})^{12-4}=(\frac{-5}{16})^8=(\frac{5}{16})^8$
c) $(\frac{5}{3})^6:(\frac{5}{3})^4=(\frac{5}{3})^{6-4}=(\frac{5}{3})^2$
d)
$(\frac{9}{7})^9:(\frac{-9}{-7})^3=(\frac{9}{7})^9:(\frac{9}{7})^3$
$=(\frac{9}{7})^{9-3}=(\frac{9}{7})^4$