physics
posted by kinematics .
An ice sled powered by a rocket engine starts from rest on a large frozen lake and accelerates at +40 ft/s2. After some time t1, the rocket engine is shut down and the sled moves with constant velocity v for a time t2. If the total distance traveled by the sled is 17 500 ft and the total time is 90 s, find the times t1 and t2

t1 + t2 = 90
(1/2)a*t1^2 + a*t1*t2 = 17,500
You know that a = 40. That leaves you with two equations in two unknowns to solve.