All numbers that are between 10 and 20 and give remainder 2 when divided by 3

If you were to divide numbers by 3, the ones that would give a remainder of 2 would be 1 number away from the next value I the multiplication table of 3 because 3 - 2 = 1. For example, 8 is a value that gives a remainder of 2 when divided by 3 because it is 1 less than 9. This means that your numbers are:
11, 14, and 17

I hope this helps!