Answer:
Since we knew that the triangles are similar, we have:
19/38 = (x + 7)/(3x + 3)
=> 1/2 = (x + 7)/(3x + 3)
=> 3x + 3 = (x + 7) . 2
=> 3x + 3 = 2x + 14
=> 3x - 2x = 14 - 3
=> x = 11
