Answer my problem with solution and final answer. Differential equation.

A man with a parachute jumps at a great height from an airplane moving horizontally. After 10 seconds, he opens his parachute. Find the velocity at the end of 15 seconds and his terminal velocity (i.e., the approximate velocity with which he will oat to the ground). Assume that the combined weight of man and parachute is 160 pounds, and the force of the air resistance is proportional ti the rst power of the velocity, equaling 1/2 v when the parachute is closed and 10v when it is opened.