\[ y(x) \left (f(x) g(x)+g'(x)\right )+f(x) y''(x)+g(x) y'(x)+y^{(3)}(x)=0 \] ✗ Mathematica : cpu = 0.0117768 (sec), leaf count = 0 , could not solve
DSolve[y[x]*(f[x]*g[x] + Derivative[1][g][x]) + g[x]*Derivative[1][y][x] + f[x]*Derivative[2][y][x] + Derivative[3][y][x] == 0, y[x], x]
✗ Maple : cpu = 0. (sec), leaf count = 0 , result contains DESol
\[\{y \left (x \right ) = \mathit {DESol}\left (\left \{\left (\frac {d}{d x}\textit {\_Y} \left (x \right )\right ) g \left (x \right )+\left (\frac {d^{2}}{d x^{2}}\textit {\_Y} \left (x \right )\right ) f \left (x \right )+\left (f \left (x \right ) g \left (x \right )+\frac {d}{d x}g \left (x \right )\right ) \textit {\_Y} \left (x \right )+\frac {d^{3}}{d x^{3}}\textit {\_Y} \left (x \right )\right \}, \left \{\textit {\_Y} \left (x \right )\right \}\right )\}\]