\[ \boxed { \left ( {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) \right ) \left ( x-y \left ( x \right ) \right ) -h \left ( {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) \right ) =0} \]
Mathematica: cpu = 0.753596 (sec), leaf count = 75 \[ \text {Solve}\left [\left \{x=\int \frac {\exp \left (-\int _1^{\text {K$\$$6747475}} \frac {K[3]-1}{h(K[3])} \, dK[3]-c_1\right )}{h(\text {K$\$$6747475})} \, d\text {K$\$$6747475}+c_2,y(x)=x-\exp \left (-\int _1^{\text {K$\$$6747475}} \frac {K[3]-1}{h(K[3])} \, dK[3]-c_1\right )\right \},\{y(x),\text {K$\$$6747475}\}\right ] \]
Maple: cpu = 0.078 (sec), leaf count = 39 \[ \left \{ y \left ( x \right ) =x+{\it RootOf} \left ( -x+\int ^{{\it \_Z} }\! \left ( -1+{\it RootOf} \left ( \int ^{{\it \_Z}}\!{\frac {{\it \_a} -1}{h \left ( {\it \_a} \right ) }}{d{\it \_a}}+\ln \left ( -{\it \_g} \right ) +{\it \_C1} \right ) \right ) ^{-1}{d{\it \_g}}+{\it \_C2} \right ) \right \} \]