3. A driver's path when diving off of a platform is given by h(t)=-5t^2+10t+20, where h(t) is the distance above water, in feet, and t is the time from the beginning of the dive, in seconds.
3a. How high is the diving platform?
3b. After how many seconds is the diver 25 feet above water?
3c. When does the diver enter the water?