Answer:
28 = x
Explanation:
We have two similar triangles. The ratio of the sides must be in the same proportion
12 8
------- = -------
x-7 14
Using cross products
12 * 14 = 8(x-7)
168 = 8(x-7)
Divide each side by 8
168/8 = 8(x-7)/8
21 = x-7
Add 7 to each side
21+7 = x-7+7
28 = x