Answer:
9
Step-by-step explanation:
If you draw a segment parallel to a side of triangle that intersects two sides of the triangle, that segment divides the intersected sides into segments of proportional lengths.
9/72 = (3x - 20)/56
1/8 = (3x - 20)/56
3x - 20 = 1/8 * 56
3x - 20 = 7
3x = 27
x = 9
Answer: 9
