Quantities x, y, z and t satisfy z = f(x,y) x = g(t) y = h(t)

Knowing that g(4) = -3, g'(4)= 0,

h(4) = 3, h'(3) = -1,

f'x(-3,3) = 2, f'y(-3,3) = 0

calculatedtdz when t=4.