Since CX and BY are both heights of the triangle, we have two ways of finding the area of the triangle:

1) AB * CX ÷ 2

2) AC * BY ÷ 2

Since both of these are the area of the traingle, therefore the two values must be equal.

We know the values of AC, BY and AB.

70 * 60 = CX * 75

CX = 56

The trick with these types of problems is that when you see the height drawn out, try to find the area.

Sidenote: did you find the value of AY, YC, and BC by yourself, since it wasn't on the image, but it was typed out?