Since a straight line is 180° (completely flat), set an equation equal to 180. The angles in blue are supplementary. The lines are parallel as indicated in red, so you can add both known values and solve. You want to isolate the variable x to one side. 118 + (8x + 6) = 180 -118 from both sides 8x + 6 = 62 -6 from both sides 8x = 56 Divide both sides by 8 x = 7
Substitute this value back into the equation to check the answer: (8(7) + 6) + 118 = 180 62 + 118 = 180 180 = 180, true!!
