Is a 25% discount on an item that originally cost de dollars the same as multiplying the original amount D by threeforce explain how you know give an example to support your answer

The volume of a spherical hot air balloon v(r) = 4 3 ? r3 changes as its radius changes. the radius is a function of time given by r(t) = 3t. find the instantaneous rate of change of the volume with respect to t at t = 2.