Answer:
x[f]=at^2/2+v[i]t+x[i]
Brackets dennote a subscript.
You're given x[f], a, t,and v[i]. You can just plug in their values into the formula and solve for x[i]. The horizontal velocity is irrelevant, the height of the tower is the initial position of the arrow, and final position is gonna be when it reaches the ground,or 0.
