Theres 60 seconds in a minute. If it takes her 5 minutes, multiply 60 by 5. you will get 300. then all you will do is divide the meters by 300 seconds. you will get the answer of 1.5 metres per second.
Guess this is how it should look like, not sure what the instructions on drawing an x through the segments mean, but hope this helps!
Factoring, you have
h(t) = -16(t^2 -2 -8) = -16(t -4)(t +2)
The ball hits the ground when h(t) = 0, so
0 = -16(t -4)(t +2)
t = 4 or -2
The positive solution is the one of interest.
It will take 4 seconds for the ball to hit the ground.