Answer:
x=4
Step-by-step explanation:
Consecutive sides in a trapezoid are supplementry, which means they add up to 180. So, your equation is 14x-15+139=180
14x+124=180 (first make the numbers as clean as you can on both sides)
14x=56 (move all of the numbers to one side, so subtract 124 from both sides)
x=4 (simplify to get your answer, so divide by 14)
(hope this helps :P)
