solve for x using parallel lines and angles

Answer:
x = 20
Step-by-step explanation:
The 2 given angles are adjacent on a straight line and sum to 180° , then
123 + 2x + 17 = 180
140 + 2x = 180 ( subtract 140 from both sides )
2x = 40 ( divide both sides by 2 )
x = 20