Mike found the difference between 18 and a number, n. Which is the correct expression and difference if n = 6?
18 – n; when n = 6 the value is 12.
18 + n; when n = 6 the value is 24.
18 + n; when n = 6 the value is 12.
18 – n; when n = 6 the value is 24.