tell me your answer

一個糖果有一個糖果紙,
一個糖果 1元;

現在商店在作促銷,3個糖果紙可以換 1個糖果;
請問15 元最多可以吃幾個糖果？

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

there's a wrapper for each sweet (gula-gula), and each sweet costs RM1.

the store is doing promotion now: 3 sweets' wrappers are entitled to 1 free sweet;

so, how many sweets can you get with RM15?