Question

two-thirds of a number plus 5 is greater than 12. find the number?

Answer 1

There are literally infinite answers to this starting with 11.  2/3 of 11 is 7.3+5 =12.3.

Every number higher than 11 would apply (actually anything over 10.5 applies but I'm speaking in whole numbers).  I think you need more info for this question.