ODE No. 80

$$(1-f^{\prime }(x))\cos (y(x))-f^{\prime }(x)+f(x)\sin (y(x))+y^{\prime }(x)-1=0$$ ✓ Mathematica : cpu = 0.0668998 (sec), leaf count = 72

DSolve[-1 + f[x]*Sin[y[x]] + Cos[y[x]]*(1 - Derivative[1][f][x]) - Derivative[1][f][x] + Derivative[1][y][x] == 0,y[x],x]
 

$$\left\{\{y(x)\to 2{\tan }^{-1}(f(x)+\frac{1}{\exp ({\int }_1^x-f(K[1])dK[1]){\int }_1^x-\exp (-{\int }_1^{K[2]}-f(K[1])dK[1])dK[2]+c_1\exp ({\int }_1^x-f(K[1])dK[1])})\}\right\}$$ ✓ Maple : cpu = 1.389 (sec), leaf count = 41

dsolve(diff(y(x),x)+f(x)*sin(y(x))+(1-diff(f(x),x))*cos(y(x))-diff(f(x),x)-1 = 0,y(x))
 

$$y\left(x\right)=2\arctan \left(\frac{-{\mathrm{e}}^{\int f\left(x\right)dx}+(\int {\mathrm{e}}^{\int f\left(x\right)dx}dx)f\left(x\right)+f\left(x\right)c_1}{c_1+\int {\mathrm{e}}^{\int f\left(x\right)dx}dx}\right)$$