A spherical weather balloon is being inflated. Beginning at 26 cm, the radius of the balloon is increasing at the rate of 5 cm per second.

A spherical weather balloon is being inflated. Beginning at 26 cm, the radius of the balloon is increasing at the rate of 5 cm per second. Express the surface area of the balloon as a function of time t (in seconds). If needed you can enter pi as pi. (Hint: The surface area of a sphere is 4 pi r^2)