Wendy had $$30$$ stickers. First, she gave Aiden $3$ stickers. Then, she gave Terry $7$ stickers. Now, each of the three people has the same number of stickers. At the beginning, how many stickers did they have in total? 
Overseas Competition->Knowledge Point->Word Problem Modules->Inverse Operation Problems
Now, Wendy has $30-3-7=20$ stickers. Thus, all of them have $20\times3=60$ stickers, which is equal to the total number of stickers they had at the beginning. 