It’s 2n - 6 = 12. The 2 represents the doubling of a number (n is the variable that stands for any number) and the - 6 is the subtracting six part of the problem to get 12. If you take the 6 and move it to the other side (adding it to the 12) which gets you 18 and then divide that by 2 to get the variable n by itself, you’ll get n = 9.