|9 - 11| = x
The || signify absolute value. 9 is "decreased by" (subtracted by) 11. X is the variable, which is the solution. The solution to this problem is 2, not -2, because absolute value only includes real numbers, in other words, it is the distance away from zero. 9 - 11 = -2 but because we want an absolute value, x = 2 in the equation above.