You can put this solution on YOUR website! if 3 is added to a number and the sum is tripled, the result is 13 more than the number.
3(3 + x) = 13 + x
9 + 3x = 13 + x
Collect like terms:
3x - x = 13 - 9
2x = 4
x = 2
The number is 2.
Hope this helps
:-)