the first step for absolute value equations is to isolate the expression contained within the absolute value bars:
3|2x+4|-1 = 11
3|2x+4| = 12
|2x+4| = 4
so |2x+4| is 4 units away from 0 on a number line, but we don't know in which direction -- negative or positive? you'll have two answers.
2x+4 = 4
AND
2x+4 = -4
solve both of those two step equations and you'll get
x = 0
AND
x = -4
so 0 and -4 are your solutions.
