$b/\dfrac{-11^5.13^7}{11^5.13^8}$
$=\dfrac{(-1).11^5.13^7}{11^5.13^8}$
$=\dfrac{(-1)}{13}$
$d/\dfrac{5^{11}.7^{12}+5^{11}.7^{11}}{5^{12}.7^{12}+9.5^{11}.7^{11}}$
$=\dfrac{5^{11}.7^{11}(7+1)}{5^{11}.7^{11}(5.7+9)}$
$=\dfrac{5^{11}.7^{11}.8}{5^{11}.7^{11}.44}$
$=\dfrac{8}{44}$
$=\dfrac{2}{11}$