document.write( "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? \n" ); document.write( "
Algebra.Com's Answer #545220 by ewatrrr(24785)\"\" \"About 
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15+21 = 36
\n" ); document.write( "36-24 = 12
\n" ); document.write( "12(both), 3(cup), 9(plate)
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