Question

|2x+6|-6=3

Answer 1

|2x+6| = 2x+6 or -2x-6
a) 2x+6-6=3 => 2x=3 => x = 3/2
b) -2x-6-6=3 => -2x-12=3 => -2x = 15 => x = -15/2

I'm not sure though, you should replace the values and see if it's a true equality.

Answer 2

(1) transpose the constant on the left side of the equation to the right side of the equation

| 2x + 6 | -6 = 3 --> |2x +6| =9

(2) using the the property |a +b| = c, then a+b=c and a+b=-c

solve...
2x+6 = 9

2x+6 = -9