Use the idea: | x - m | = d
where m is the midpoint between the two answers
and d is the distance from the midpoint to either of the two answers.
To find the midpoint, find the average of the two answers; in this case: m = (3 + 11) = 2 = 14 / 2 = 7.
For this problem the distance from the midpoint to an answer is: d = 7 - 3 = 4.
An absolute value equation that has solutions of 3 and 11 is: | x - 7 | = 4