SOLUTION: There are 24 trays on a table in the cafeteria. Each tray contains a cup only, a plate only, or both a cup and a plate. If 15 of the trays contain cups and 21 of the trays contain

Algebra ->  Equations -> SOLUTION: There are 24 trays on a table in the cafeteria. Each tray contains a cup only, a plate only, or both a cup and a plate. If 15 of the trays contain cups and 21 of the trays contain       Log On


   

Question 899133: There are 24 trays on a table in the cafeteria. Each tray contains a cup only, a plate only, or both a cup and a plate. If 15 of the trays contain cups and 21 of the trays contain plates, how many contain both a cup and a plate?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
15+21 = 36
36-24 = 12
12(both), 3(cup), 9(plate)