Question

mathhh heeeeeeeeelp please

Answer 1

\[\LARGE (8\cdot 10^7)\cdot (5\cdot 10^{-5})=\]
\[\LARGE 8\cdot 5\cdot 10^7\cdot 10^{-5}=\]
\[\LARGE 40\cdot 10^{7+(-5)}=4\cdot 10\cdot10^2= \]
\[\LARGE 4\cdot 10^{2+1}=4\cdot 10^3\]