We have to make ALL the units equal.
So, we could calculate 14" by 18" by 7" = 1,764 cubic inches
ORwe could calculate 1.1666666666 by 1.5 by 0.5833333333 = 1.0208333333cubic feetthere are 1,728 cubic inches i a cubic foot so this equals 1.0208333333 * 1,728 = 1,764 cubic inches
So, both answers are correct.