The volume of a cube increases at a constant rate of 10cm^3 per second . Find the rate of change in its total surface area at the instant when the sides are 20cm long.

I know that rate of change means I have to involve derivatives. The surface area formula for a cube = the length of a side say (x^2) x6 and the volume of a cube is x^2 x height .

I don't know how to form an equation in terms of time.

Please Help