Answer:
x = 11
Explanation:
Because the triangles are similar, the following is true:
12 2x + 5
--- = -------------------
8 x + 7
Cross multiplying produces the following equation:
12x + 84 = 16x + 40.
Combining the x terms, we get 84 = 4x + 40
Combining the constant terms, we get 4x = 44, so that x = 11.