At a certain point in time, each dimension of a cube of ice is 30 cm and is decreasing at the rate of 2 cm/hr. how fast is the ice melting (losing volume)?

Let each side of the cube be of length x

x = 30 cm

dx/dt = -2 cm/hr

V = x^3 differentiate with respect to time 

dV/dt = 3x^2 dx/dt = 3 * (30)^2 * (-2) = -5400 cm^3/hr