3.5 determine the missing value C, the number of cans required ?

To determine the missing value C, the number of cans required, we need to know the total number of cans and the number of cans already used.

For example, if the total number of cans is 10 and 6 cans have already been used, then the missing value C would be:

C = Total number of cans - Number of cans already used
C = 10 - 6
C = 4

Therefore, the missing value C, the number of cans required, would be 4 in this example.