You are purchasing soft drinks for the company annual party. you expect about 32 people to be there. you want to allow at least 18 ounces per person. store a offers 24-12 ounce cans for $5.89. store b offers 12-12 ounce cans for $3.79.

For A, a number of cases, presuming you are planning on pouring these in cups of 18 oz, you would need to buy 2 cases. One case allows for 16 people to have 18oz cups of soda. This is because by multiplying 24 by 12 to get the total number of oz's in a case, you get 288, which can be divided by 18oz to show how many this would serve. The total cost to buy this would be 
$11.78 (Two cases)

For B, the number of cases, presuming you are planning on pouring these into cups of 18oz cups, you would need to buy 4 cases. This is because by multiplying 12 by 12, to get the total oz's in a case, then dividing by 18oz, you get 8. Which can be multiplied by 4 to get the number of cases you need, as one case serves 8 people. So you need to buy 4 cases, at the total cost of $15.16

So ultimately the cheapest price for the desired amount of soda, would be plan A, at a cost of $11.78