Answer:
18 stickers.
Explanation:
Cindy buys 18 more stickers in the start. This results in 13+18= 31 stickers. She then gets five for her birthday. 31+5=36 so she now has 36 stickers but she then gives eight away which means she has 36-8=28 stickers. She uses ten stickers to decorate so Cindy has 28-10=18 stickers left