Hello! To start you want to look for the multiples of 15, under 100. List these out and look for the multiple that when you add the digits together it makes 12.
Answer:
The multiples of 15 under 100: 15,30,45,60,75,90
Sum of digits,
1+5 = 6
3+0 = 3
4+5 = 0
6+0 = 6
7+5 = 12
9+0 = 9
The number is 75
