\[ \left \{x'(t)+3 x(t)-y(t)=e^{2 t},x(t)+y'(t)+5 y(t)=e^t\right \} \] ✓ Mathematica : cpu = 0.0475309 (sec), leaf count = 83
\[\left \{\left \{x(t)\to \frac {1}{900} e^{-4 t} \left (900 \left (c_1 (t+1)+c_2 t\right )+36 e^{5 t}+175 e^{6 t}\right ),y(t)\to \frac {1}{900} e^{-4 t} \left (-900 \left (\left (c_1+c_2\right ) t-c_2\right )+144 e^{5 t}-25 e^{6 t}\right )\right \}\right \}\]
✓ Maple : cpu = 0.073 (sec), leaf count = 64
\[ \left \{ \left \{ x \left ( t \right ) ={{\rm e}^{-4\,t}}{\it \_C2}+{{\rm e}^{-4\,t}}t{\it \_C1}+{\frac {7\,{{\rm e}^{2\,t}}}{36}}+{\frac {{{\rm e}^{t}}}{25}},y \left ( t \right ) =-{\frac {{{\rm e}^{2\,t}}}{36}}-{{\rm e}^{-4\,t}}{\it \_C2}-{{\rm e}^{-4\,t}}t{\it \_C1}+{{\rm e}^{-4\,t}}{\it \_C1}+{\frac {4\,{{\rm e}^{t}}}{25}} \right \} \right \} \]