Partial Derivatives & the Gradient · Medium problem

A differentiable function $f(x,y)$ has $f_x(x,y) \equiv 2$ and $f_y(x,y) \equiv 3$ at EVERY point (so $f$ is necessarily of the form $f=2x+3y+C$ for some constant $C$). Given $f(1,1)=10$, find $f(4,-2)$.