The value of $$a^{\log _b c}-c^{\log _b a}$$, where $$a, b, c>0$$ but $$a, b, c \neq 1$$, is

The value of $${3^{{{\log }_4}5}} - {5^{{{\log }_4}3}}$$ is

$${8^{3{{\log }_8}5}}$$ is equal to