1. The problem statement, all variables and given/known data Calculate ∂f/∂s + ∂f/∂t at s = 2, t = -1. Given: f = f(x,y) x = s - t y = s2 + t2 ∂f/∂x (3,5) = 0.06170 ∂f/∂y (3,5) = 0.06170 2. Relevant equations ∂f/∂s = ∂f/∂x * ∂x/∂s + ∂f/∂y * ∂y/∂s ∂f/∂t = ∂f/∂x * ∂x/∂t + ∂f/∂y * ∂y/∂t 3. The attempt at a solution I calculated: ∂x/∂s = s = 2 ∂x/∂t = t = -1 ∂y/∂s = 2s = 4 ∂y/∂t = 2t = -2 I know I haven't gotten far, but I don't know how to get ∂f/∂x or ∂f/∂y from the given equations.