Answer:
We know that C is the total number of cans in a complete case.
Victoria counts:
16 full cases, so in those we have: 16*C cans.
4 cases with 5 missing cans, so in those we have:
Then if each case has C cans, the cases that are missing 5 cans have:
C - 5 cans.
Then in those four cases we have a total of: 4*(C - 5) cans.
And Victoria knows that there are 220 cans, then we have that:
16*C + 4*(C - 5) = 220
16*C + 4*C - 20 = 220
16*C + 4*C = 220 + 20 = 240
20*C = 240
C = 240/20 = 12
Then each case has 12 cans.
Then the number of cans in the cases with missing cans is:
12 cans - 5 cans = 7 cans.
