additional maths

given that G(x) = g[f(x)] and f(1) = 2. If d/dx [f(x)] = 3 at x = 1, and d/dx [g(x)] = 5 at x=2, find d/dx [G(x)] at x = 1.
dG(x) /dx
=[d g[f(x)] /df(x)][df(x)/dx]
since f(1) = 2, d/dx [f(x)] = 3 at x = 1, d/dx [g(x)] = 5 at x=2
so
at x = 1
dG(x) /dx
=5*3
=15