Explain how to find the general solution to the given ODE.
\[ 3 \, {y} = 18 \, \cos\left(-2 \, t\right) e^{t} + 3 \, {y'} \]
Answer:
\[ {y} = k e^{t} + 3 \, e^{t} \sin\left(-2 \, t\right) \]