\[
\boxed{
 \left\{ 3\,{\frac {\rm d}{{\rm d}t}}x \left( t \right) +7\,{\frac {\rm d}{{\rm d}t}}y \left( t \right) +8\,x \left( t \right) +24\,y \left( t \right) ={{\rm e}^{2\,t}},4\,{\frac {\rm d}{{\rm d}t}}x \left( t \right) +9\,{\frac {\rm d}{{\rm d}t}}y \left( t \right) +11\,x \left( t \right) +31\,y \left( t \right) ={{\rm e}^{t}} \right\} }
\]