The tens digit of a two-digit number is five more than the units digit. the sum of the digits is 9. find the number.

B=A+5
10A+B=3(A+B)
Replace the B’s in the bottom equation with A+5s, because we know that’s the same thing from the top equation

10A+A+5=3(A+A+5)
11A+5=3(2A+5)
11A+5=6A+15
5A=10
A=2
Then B is 5 more than that so B=7
Your number is 27
**To double check**
When we double check this and see 7 is 5 more than then 2. Then 27 is three times what we get when we add the digits (2+7=9).