Answer:
x = 7
Explanation:
If the triangles are similar, the side length ratios have to be the same
49 63
------------- = ---------
42 8x-2
Using cross products
49 ( 8x-2) =42 (63)
Divide each side by 49
8x-2 = 42*63/49
8x -2 = 54
Add 2 to each side
8x = 56
Divide b 8
8x/8 = 56/8
x = 7