If B is the midpoint of AC, then AB=BC. It is also BC=AC-AB
AB = x + 6
AC = 5x - 6
BC = (5x - 6) - (x + 6)
We can kinda use distributive property, like this:
BC = 5x - 6 -x - 6
Combine like terms:
BC = 4x - 12
To verify, we can add AB and BC to see if their sum is equal to AC.
(x + 6) + (4x - 12) = 5x - 6
If we are correct, this equation will be true.
x + 6 + 4x - 12 = 5x - 6
Combine like terms:
6 + 5x - 12 = 5x - 6
5x - 6 = 5x - 6
It's correct!
BC = 4x - 12. Final Answer.
Let me know if you have any questions about this! :)