\[ 5^8 \cdot 5^7 = 5^{8+7} = 5^{15} \]
\[ \frac{2^5 \cdot 8}{4^3} = \frac{2^5 \cdot 2^3}{(2^2)^3} = \frac{2^{5+3}}{2^{2 \cdot 3}} = \frac{2^8}{2^6} = 2^{8-6} = 2^2 = 4 \]
Ответ: а) 5ⁱ⁵; б) 4.