Question 659204
For this one, you just need to make a list of the possibilities described and then test to see which meets the rest of the specifications in the problem.

There are only a few 2 digit numbers where the tens is one more than the unit's digit.

10
21
32
43
54
65
76
87
98

No, we'll add the sum of the digits in another column.


10    1
21    3
32    5
43    7
54    8
65    9
76    13
87    15
98    17

You probably didn't need to complete the list before seeing the answer. You might even have suspected it after looking at the first list because it is the only number in the list evenly divisible by 7.

21/3=7