\[ \left \{x'(t)=a x(t),y'(t)=b\right \} \] ✓ Mathematica : cpu = 0.0162797 (sec), leaf count = 22
\[\left \{\left \{x(t)\to c_1 e^{a t},y(t)\to b t+c_2\right \}\right \}\] ✓ Maple : cpu = 0.051 (sec), leaf count = 19
\[\{x \relax (t ) = c_{1} {\mathrm e}^{a t}, y \relax (t ) = b t +c_{2}\}\]