\begin{enumerate}
\begin{multicols}{2}
\item $\begin{aligned}[t]
\dfrac{\e^6\times\e^4}{\e^{-8}} & =\dfrac{\e^{6+4}}{\e^{-8}}\\
& = \dfrac{\e^{10}}{\e^{-8}}\\
& = \e^{10-(-8)}\\
& = \e^{10+8}\\
\Aboxed{\dfrac{\e^6\times\e^4}{\e^{-8}} & = \e^{18}}
\end{aligned}$

\item $\begin{aligned}[t]
\big(\e^{-2}\times\e^{5}\big)^3 & = \big(\e^{-2+5}\big)^{3}\\
& = \big(\e^3\big)^3\\
& = \e^{3\times3}\\
\Aboxed{\big(\e^{-2}\times\e^{5}\big)^3  & = \e^9}
\end{aligned}$

\item $\begin{aligned}[t]
\dfrac{\e^{-1}\times\e^{3}\times\e^{-2}}{\big(\e^{-5}\big)^{-2}\times\e^{-9}} & = \dfrac{\e^{-1+3-2}}{\e^{-5\times(-2)}\times\e^{-9}}\\
& = \dfrac{\e^0}{\e^{10-9}}\\
& = \dfrac{1}{\e^1}\\
\Aboxed{\dfrac{\e^{-1}\times\e^{3}\times\e^{-2}}{\big(\e^{-5}\big)^{-2}\times\e^{-9}} & = \e^{-1}}
\end{aligned}$

\item $\begin{aligned}[t]
\left(\dfrac{\e^6}{\e^3}\right)^2\times\e^{-2} & = 
\big(\e^{6-3}\big)^2\times\e^{-2}\\
& = \e^{3\times2}\times\e^{-2}\\
& = \e^{6-2}\\
\Aboxed{\left(\dfrac{\e^6}{\e^3}\right)^2\times\e^{-2} & = \e^4}
\end{aligned}$
\end{multicols}
\end{enumerate}