If you would like to find the number, you can calculate this using the following steps:
n = ? ... a number
3 times a number plus 12 minus 5 times the same number is 22
3 * n + 12 - 5 * n = 22
3 * n - 5 * n = 22 - 12
-2 * n = 10
2 * n = -10
n = -10/2
n = -5
The correct result would be -5.