We have to calculate the maximum common divisor of these 3 numbers in order to know what is the maximum ammount of sandwiches they can make.
We can list the factors of each number:
72: 1, 2, 3, 4, 6, 8, 12, 18, 24, 36, 72.
48: 1, 2, 3, 4, 6, 8, 12, 16, 24, 48.
96: 1, 2, 3, 4, 6, 8, 12, 16, 24, 48, 96.
To calculate this factors, we start by dividing by 2 and 3, and so on, and checking if the result is a whole number. If it is, the denominator is a factor.
The maximum common divisor is 24, so they can make 24 sandwichs, each one with 72/24=3 slices of turkey, 48/24=2 slices of cheese and 96/24=4 slices of tomatoes.
George's boxes
He has bought boxes at different prices.
3 boxes at $3.50 and 4 boxes at $3.00.
The cost of the first group of boxes is 3 boxes x 3.50 $/boxes = $10.50.
The cost of the second group is 4 boxes x 3.00 $/boxes = $12.
Then, if we add the cost, it is 10.50 + 12 = $22.50.
If we write it in the blanks we have:
3 boxes * 3.50 = 3 * 3.50
4 boxes * 3.00 = 4 * 3.00
(3 * 3.50) + (4 * 3.00) = 22.50
(underlined is what goes in the blanks)