\[ \left \{x'(t)+3 x(t)-y(t)=e^{2 t},x(t)+y'(t)+5 y(t)=e^t\right \} \] ✓ Mathematica : cpu = 0.0777104 (sec), leaf count = 162
\[\left \{\left \{x(t)\to -e^t (t+1) \left (\frac {t}{5}+\frac {1}{36} e^t (6 t-7)-\frac {1}{25}\right )+e^t t \left (\frac {t}{5}+\frac {1}{36} e^t (6 t-1)+\frac {4}{25}\right )+c_1 e^{-4 t} (t+1)+c_2 e^{-4 t} t,y(t)\to e^t t \left (\frac {t}{5}+\frac {1}{36} e^t (6 t-7)-\frac {1}{25}\right )-e^t (t-1) \left (\frac {t}{5}+\frac {1}{36} e^t (6 t-1)+\frac {4}{25}\right )-c_1 e^{-4 t} t-c_2 e^{-4 t} (t-1)\right \}\right \}\] ✓ Maple : cpu = 0.116 (sec), leaf count = 64
\[ \left \{ \left \{ x \left ( t \right ) ={{\rm e}^{-4\,t}}{\it \_C2}+{{\rm e}^{-4\,t}}t{\it \_C1}+{\frac {{{\rm e}^{t}}}{25}}+{\frac {7\,{{\rm e}^{2\,t}}}{36}},y \left ( t \right ) =-{\frac {{{\rm e}^{2\,t}}}{36}}-{{\rm e}^{-4\,t}}{\it \_C2}-{{\rm e}^{-4\,t}}t{\it \_C1}+{{\rm e}^{-4\,t}}{\it \_C1}+{\frac {4\,{{\rm e}^{t}}}{25}} \right \} \right \} \]