The Chain Rule & Implicit Differentiation · Easy problem

A differentiable function $f(x,y)$ has $f_x(1,2) = 3$ and $f_y(1,2) = -1$. A particle moves along $x = t^2$, $y = 2t$. Find the rate of change of $f$ along the path, $\dfrac{d}{dt}f(x(t),y(t))$, at $t = 1$.