\[ (a+x y(x)) y'(x)+b y(x)=0 \] ✓ Mathematica : cpu = 0.0775916 (sec), leaf count = 33
\[\text {Solve}\left [x=\frac {e^{-\frac {y(x)}{b}} \left (b c_1-a \text {Ei}\left (\frac {y(x)}{b}\right )\right )}{b},y(x)\right ]\]
✓ Maple : cpu = 0.051 (sec), leaf count = 30
\[ \left \{ {\it \_C1}+ \left ( -{{\rm e}^{{\frac {y \left ( x \right ) }{b}}}}bx+a{\it Ei} \left ( 1,-{\frac {y \left ( x \right ) }{b}} \right ) \right ) ^{-1}=0 \right \} \]