Sharon has $$94$$ watermelons and $$138$$ pineapples. Every day, she will use $$9$$ watermelons and $$9$$ pineapples to make fruit juice. After~\uline{~~~~~~~~~~}~days, the number of pineapples left will be $$3$$ times of the number of watermelons left. 
Overseas Competition->Knowledge Point->Word Problem Modules->Questions Involving Sum, Difference and Multiples->Problems of Difference and Multiple