Since the numbers of boxes are 45, 18, 36
Since we need to know the greatest number of boxes in each pack
Then we have to find the greatest common factor of 45, 18 and 36
Let us list the factors of each number
Then the factors of 45 are: 1, 3, 5, 9, 15, 45
Then the factors of 18 are: 1, 2, 3, 6, 9, 18
Then the factors of 36 are: 1, 2, 3, 4, 6, 9, 12, 18, 36
From the 3 lists, we can see the common factors of 45, 18, 36 are
1, 3, 9
Since the greatest factor is 9, then
The greatest number of boxes in each pack is 9