For a banquet Ivana bought several dozen roses and several dozen carnations. The roses cost 20 dollars per dozen, and the cammations cost 12 dollars per doven: Ivana bought a total of 15 dozen flowers and paid a total of $260). How many roses did she buy?
+592 x dozen roses and y dozen carnations
20x+12y=260
x+y=15
8x=80
x=10
10x12=$\boxed{120}$
