That line that contains labeled angles is a straight angle and straight angles are 180 degrees. So you would do 72 + x+4=180 (you can remove the parenthesis because + * + = +). Simplify the equation to x+76=180. subtract 76 from both sides and get x=104 degrees as your final answer.
A line like this will always have a measure of 180 degrees, therefore when the two sides are combined, it must equal 180, which means you can set up an equation and x can be determined
