\[ f(x) y(x)-g(x)+y'(x)=0 \] ✓ Mathematica : cpu = 0.471675 (sec), leaf count = 62
\[\left \{\left \{y(x)\to c_1 e^{\int _1^x -f(K[1]) \, dK[1]}+e^{\int _1^x -f(K[1]) \, dK[1]} \int _1^x g(K[2]) e^{-\int _1^{K[2]} -f(K[1]) \, dK[1]} \, dK[2]\right \}\right \}\]
✓ Maple : cpu = 0.019 (sec), leaf count = 24
\[ \left \{ y \left ( x \right ) = \left ( \int \!g \left ( x \right ) {{\rm e}^{\int \!f \left ( x \right ) \,{\rm d}x}}\,{\rm d}x+{\it \_C1} \right ) {{\rm e}^{\int \!-f \left ( x \right ) \,{\rm d}x}} \right \} \]