18 + n
the sum of 18 and a number equals 24
9x+10
3(x=12)
2(n+3)
3x+2
The sum is 32
6+n = 2n+5
14
"The sum of a number and three times another number is 18. find the numbers if their product is a maximum?"
18. The sum of its digits is 9. And yes, it is unique.
18
If the number is even and the sum of its digits is divisible by nine then the number is divisible by 18.