\begin{exerciseStatement}
Explain how to find the general solution to the given ODE.
\[ -{y} = {y'} + 3 \, e^{\left(-t\right)} \]
\end{exerciseStatement}
\begin{exerciseAnswer}
\[ {y} = k e^{\left(-t\right)} - 3 \, t e^{\left(-t\right)} \]
\end{exerciseAnswer}