Mario's locker number is between 80 and 99. the sum of the digits is 13. the tens digit is 3 more than the ones digit. what is mario's locker number?

Since we know it is between 80 and 99, the tens place can only either be 8 or 9.

If it is 8, the ones place is 5 since the digits must add to 13.
If it is 9, the ones place is 4 since, once again, the digits must add to 13.

Our options are 85 or 94. Based on the last clue, it is 85 since 8-5=3.

Final 85