According to the first and second statements the only possibilities are 3, 9, 15, 21, 27 and 33.
If the third statement then says that it is smaller than 28 (7x4) then the remaining numbers off the list are 3, 9, 15, 21 and 27.
It then says that the tens digit has to be even so then the numbers 3 and 9 are immediately scraped off (because they don't have a tens digit!) leaving 15, 21 and 27. 15 has the tens digit 1 which is not even leaving the only two possibilities 21 and 27.
The last statement then says it is the bigger of the two and that is 27. So the number is 27.