We know that the number of marbles is represented by n. We also know that as the number of marbles increases, the volume of water W(n) decreases, since 0.05n is subtracted.
Since 0.05n is subtracted from 32, then 32 must be the original amount of water used if there are no marbles.
Since the amount of water decreases by 0.05 times the number of marbles, the volume of each marble must be 0.05.
