Divide 22 by 2 to get "c" isolated.
Given that the subway stations are 930 m apart, the train have to be accerelated for half the distance and then decerelated for the rest of the distance.
Recall that the distance travelled by an object with an initial velocity, u, for a period of time, t, at an accereration, a, is given by

But, we assume that the train accelerates from rest, thus

The maximum speed is attained at half the center of the distance between subway stations (i.e. at distance = 465 m).
Thus, maximum speed = distance / time = 465 / 23.12 = 20.11 m/s.
2y to the second power= 4y
-6y to the second power= -36y
No they did not eat the whole thing. They are 6 out of 8 pieces of the orange. Therefore there is still 2 pieces left