Let z = f(x, y) where f is a differentiable function. We restrict this function to the curve with parametric equations (1 + 3t + (2, (4 - 1), teR. We also know that: fx (15, 11) = 1, fx(11, 15) = 3, fy(15, 11) = 7 fy (11, 15) = 11, fy(19, 80) = 13, fy(80, 11) = 17 fx(11, 80) = 10, fx(80, 11) = -1, fx(19, 80) = -7 fy(11, 80) = -6, fx(15, 80) = 11, fy(15, 80) = 16 Calculate of of and at t = 2 at t=3