This problem is asking for a number between 20 and 50 that has tens and ones, it could be 25, 35 or 45. Basically, the answer could be all numbers that doesn't end in zero or one, because zero means that there aren't any ones, and if ends in one, that means it only has one one.
So, the answer we choose is 45, which has 4 tens and 5 ones, that is, 4 tens that equals 40, and 5 ones that equals 5.
