You can put this solution on YOUR website! L will represent the larger number and S will represent the smaller number.
From this information, you know that L is a multiple of 3 because if you subtract 3S from it (3S is divisible by 3), you get 6 (which is also divisible by 3).
To solve this, use guess and check. You can try 21, 18, 15, or 12. (These are the numbers divisible by 3 which are greater than the number you have to add to them to equal 22.)
21 is not the answer.
Try 18:
18 is the correct answer.
To make sure, check 15 and 12.
The answer is 18.
Check: