It is known about g(t) and h(t) that g(2) = 3, h(2) = 4, g'(2) = 5, h'(2) = 6, and function f(x,y) partial derivates are fx (3, 4) = 7 fy (3, 4) = 8. Calculate composite function f(g(t), h(t)) derivative at point t=2