A sweater, the original price is 120 yuan, now buy 3 pieces and get 1 free, Xiaohong buys back such 4 pieces of clothes, how much discount is it equivalent to?
一件羊毛衫，原价120元，现在买3件送一件，小红买回这样的4件衣服，相当于打了几折？
<result>4</result>