Three (3) times (multiplication) a number (n) plus (addition) 12 minus (subtraction) 5 times (multiplication) the same number (n) is (=) 22.
3n + 12 - 5n = 22 Combine like terms (3n and -5n)
-2n + 12 = 22 Subtract 12 from both sides
-2n = 10 Divide both sides by -2
n = -5
The number is -5 .