Answer: fraction 16 over 4
Explanation:
The given graph shows the number of paintballs a machine launches, y, in x seconds.
We know that the rate of change of a line is given by :-

The ordered pairs on the line in graph are (4, 16) and (8, 32) and (12, 48) and (16, 64).
Thus, the rate per second at which the machine launches the balls is given by :-
[tex]k=\frac{32-16}{8-4}=\frac{16}{4}