Answer:
x = 4
Explanation:
the angle immediately to the left of 20x must be 25x. that's because the two lines with double arrows at the top are parallel lines.
the angle to the left of 20x and the 25x are called alternate angles. they are equal.
also, 20x and the angle to the left of it are on a straight line. angles on a straight line add up to 180°.
so, we now have 20x + 25x = 180.
45x = 180
divide both sides by 45:
x = 180/45
= 4.
x = 4.