To find the total number of pears, you need to add the number of pears Mary ate and the number of pears Carmie ate.
Mary: 4 1/2 pears = 9/2 pears
Carmie: 7 2/4 pears = 15/4 pears
Total: 9/2 + 15/4
To add these fractions, you need to find a common denominator.
The least common multiple of 2 and 4 is 4.
5/2 can be converted to 10/4.
9/2 + 15/4 = 10/4 + 15/4 = 25/4
The total number of pears in the box is 25/4, or 6 1/4.
Therefore, there were 11 1/4 pears in the box.