Let's use an example
Say we had two lines P and Q. If P has slope 2/5, then Q must have slope -5/2 in order for P and Q to be perpendicular.
Note how -5/2 is the negative reciprocal of 2/5. In other words, you flip the fraction and the sign to go from either slope.
Another thing to notice is that the two slopes multiply to -1. This is true for any pair of perpendicular lines as long as neither line is vertical.
Answer with explanation:
Since the motion of the ball is projectile motion we shall use the equations for projectile motion.
The maximum height achieved by the projectile is given by
Applying the values we get

The range of the projectile is given by

Applying values we get

thus the maximum horizontal distance reached by the ball equals 7.339 meters after which it bounces thus a person standing 8 meters away will not be able to catch it.
(The height of the players is not taken into account since no info is given about their height.)

let's plug in the value of y :
The answer is (C) but i'm not completely sure