Answer:
x = 6
Explanation:
Let's figure out the dilation of the shape.
8/2 = 4 so the triangle is dilated by 2.
Therefore, ED must be divided by 2. That makes side XY equivalent to 5 because 10/2 is 5.
x - 1 = 5 so x has to equal 6.
To check our work, let's see 3(x-1). On XYZ, the corresponding side is side XZ which is 7.5. 7.5 x 2 = 15 so 3(x-1) must equal 15.
Let's plug our 6 in.
3(6-1) = 3(5)
3(5) = 15.