I guessed and tested. I knew that they would have to have more than 22 marbles at the start. Then I thought, Maybe I'll start at thirty and work my way up.
30-22=8.
8*3=24.
Too low.
35-22=13
13*3=39
Too high.
Maybe in the middle.
33-22=11
11*3=33
Just right.
And there you have it. The answer
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