1) Let's calculate that. Start by multiplying the factors 7, and 5.
[tex]\begin{gathered} 7\cdot10^{-5}\text{ x 5 }\cdot10^{-8}= \\ 35\cdot10^{-13} \end{gathered}[/tex]After that, we use the property of the exponents when multiplying. Repeat the base and then add the exponents -8 + (-5) = -8 -5 = -13.