$\dfrac{15^6.5^4}{45^2.25^3}$
$= \dfrac{5^{10}.3^6}{3^4.5^8}$
$= \dfrac{5^2.3^2}{1}$
$= 25.9$
$=225$
$\dfrac{11.2^{11} - 10.45}{16^3}$
$= \dfrac{11.2^{11} - 2.3^2.5^2}{2^{12}}$
$= \dfrac{2.(11.2^{10} - 3^2.5^2)}{2^{12}}$
$= \dfrac{11.1024 - 225}{2048}$
$= \dfrac{11039}{2048}$