The answer: <span>the two triangles are similar in addition, the line UV is parallel to line BC, so we can use the theorem of Thales for proving the following ratios:
AV /AC = AU/ AB= UV/ BC 372/589=20x +80 / AB = 444 / 703
</span>so we get (372/589) AB - 80 = 20x, and x = ( (372/589) AB - 80 ) / 20