Hello!
The midpoint separates two equal distances,
This means that AB = BC
So lets type of the equation to solve for x:
2x + 7 = 5x -14
Lets add 14 on both sides.
2x + 21 = 5x
Lets subtract 2x on both sides.
21 =3x
Lets divide 3 by both sides
x = 7
AB= 21
2(7) + 7
14 + 7
21
BC = 21
5(7) - 14
35 - 14
21
AC = 42
21 + 21 = 42
I hope this helps, Have a great day!!