Ou have traveled 25 miles in 2 minutes and come to a standstill. what was your initial velocity?

If you traveled 25 miles in 2 minutes, your average speed was 25 miles per 2 minutes or 750 miles per hour. If your rate of deceleration was constant, your initial speed was two times 750 miles per hour or 1500 mph. 

I do not have enough information to determine your initial velocity because I don't know what direction you were going, and velocity is speed with direction.