\[
\boxed{
 \left\{ {\frac {\rm d}{{\rm d}t}}x \left( t \right) +2\,y \left( t \right) =3\,t,{\frac {\rm d}{{\rm d}t}}y \left( t \right) -2\,x \left( t \right) =4 \right\} }
\]