Answer:
49
Step-by-step explanation:
The two lengths equal each other.
6x + 7 = 8x -7 Subtract 6x from both sides
7 = 2x - 7 Add 7 to both sides
14 = 2x Divide both sides by 2
7 = x
Now that you know x, plug 7 into the first equation
6x + 7
6(7) + 7
42 + 7
49
