Hi Rom, I agreed with you when i first read the question but we interpreted it differently from intended.
This is a simplified school question. Perhaps we are intended to use calculus, or perhaps not.
I will do it without calculus.
The trajectory of a ball will be parabolic (pre-knowledge on my part). We are only interested in height and time.
The x does not refer to horizonal distance it refers to time and I am going to change it to a t make it less confusing.
So the ball is traveling in the path of a concave down parabola. (t,y) (time, height)
If you let the top of the building be the point (0,0) that is 0 time and 0 vertical height
then the ground will be ( 5,-25)
and the maximum height coordinates will be (2,20)
It is a concave down parabola and the t intercepts will be 0 and 4 (becasue it is symmetrical)
so the eqution must be
y=−a(t−0)(t−4)y=−at(t−4)Whent=2,y=20sub20=−a∗2(2−4)20=−2a∗−220=4aa=5So if the coordinates are set as I have described, I mean with the top of the buildng being height 0then y=−5t(t−4) Will model the path of the ball
I hope that helps.