5. Suppose z = f(x,y), where x = g(s,t), y = h(s, t), g(1,2) = 3, gs(1,2) = -1,gt(1,2) =4, h(1,2) = 6, h(1, 2) = -5, h(1,2) = 10, fa(3, 6) = 7, and fy(3,6) =8. Find Əz/Os when s = 1 and t = 2.