In a store, set meal A is 18 yuan each, and set meal B is 21 yuan each. Xiao Ming brought 60 yuan, and he wants to buy 3 sets. How many ways can he buy?
某店A套餐每份18元，B套餐每份21元，小明带了60元，要买3份，可以有几种买法？
<result>3</result>