Answer :
[tex]0\underbrace{.07}_{\to2}=7\times10^{-2}\\\\1\underbrace{600}_{\leftarrow3}=1.6\times10^3\\\\0\underbrace{.0004}_{\to4}=4\times10^{-4}\\\\\frac{0.07\times1600}{0.0004}=\frac{7\times10^{-2}\times1.6\times10^3}{4\times10^{-4}}=\frac{7\times1.6}{4}\times10^{-2+3-(-4)}=\boxed{2.8\times10^5}[/tex]