16.181818911918626382829229228282882828282.6272882
8064 cartons in 21 days......8064/21 = 384 cartons per day
the cartons were delivered in cases of 6.....384 / 6 = 64 cases
each of 16 coffee shops received an equal number of cases..
64/16 = 4.....so each coffee shop received 4 cases per day <==
The Answer is C, my good friend.