$B = \dfrac{25^4 . 4^4}{20^5 . 5^5}$
$B = \dfrac{(5^2)^4 . (2^2)^4}{(2^2 .5)^5 . 5^5}$
$B = \dfrac{5^8 . 2^8}{2^{10} . 5^{10}}$
$B = \dfrac{1}{2^2 . 5^2}$
$B = \dfrac{1}{100}$
$C = \dfrac{2^{15} . 8^4}{4^{13}}$
$C = \dfrac{2^{15} . (2^3)^4}{(2^2)^{13}}$
$C = \dfrac{2^{27}}{2^{26}}$
$C = 2$
$D = \dfrac{9^8 . 3^{10}}{81^3 . 27^4}$
$D = \dfrac{(3^2)^8 . 3^{10}}{(3^4)^3 . (3^3)^4}$
$D = \dfrac{3^{26}}{3^{24}}$
$D = 3^2 = 9$
$E = \dfrac{3^{10} . 11 + 3^{10} . 5}{3^9 . 2^4}$
$E = \dfrac{3^{10} . (11 + 5)}{3^9 . 2^4}$
$E = \dfrac{3^{10} . 16}{3^9 . 16}$
$E = 3$
$F= \dfrac{2^{10} . 7 + 2^{10}.5}{2^8 . 3}$
$F = \dfrac{2^{10} . (7 + 5)}{2^8 . 3}$
$F = \dfrac{2^{10} . 12}{2^8 . 3}$
$F = \dfrac{2^2 . 12}{3}$
$F = 4.4=16$