Ответ:

\(\dfrac{0.9^9\cdot0.9^3}{0.9^{10}}=0.9^{9+3-10}=0.9^2=0.81\).

\(\dfrac{0.5^{12}}{0.5^5\cdot0.5^6}=0.5^{12-5-6}=0.5\).

\(0.81-0.5=0.31\).

Ответ: \(0,31\).