\[ \left \{x'(t)+3 x(t)-y(t)=e^{2 t},x(t)+y'(t)+5 y(t)=e^t\right \} \] ✓ Mathematica : cpu = 0.0482395 (sec), leaf count = 76
\[\left \{\left \{x(t)\to e^{-4 t} \left (c_1 (t+1)+c_2 t\right )+\frac {e^t}{25}+\frac {7 e^{2 t}}{36},y(t)\to e^{-4 t} \left (c_2-\left (c_1+c_2\right ) t\right )+\frac {4 e^t}{25}-\frac {e^{2 t}}{36}\right \}\right \}\]
✓ Maple : cpu = 0.096 (sec), leaf count = 64
\[ \left \{ \left \{ x \left ( t \right ) ={{\rm e}^{-4\,t}}{\it \_C2}+{{\rm e}^{-4\,t}}t{\it \_C1}+{\frac {{{\rm e}^{t}}}{25}}+{\frac {7\,{{\rm e}^{2\,t}}}{36}},y \left ( t \right ) =-{\frac {{{\rm e}^{2\,t}}}{36}}-{{\rm e}^{-4\,t}}{\it \_C2}-{{\rm e}^{-4\,t}}t{\it \_C1}+{{\rm e}^{-4\,t}}{\it \_C1}+{\frac {4\,{{\rm e}^{t}}}{25}} \right \} \right \} \]