To solve this problem, we need to know 2 relationships:
<h2>1. AC = AB + BC</h2>
The distance of AC is the sum of AB and BC.
![AC = AB + BC](https://tex.z-dn.net/?f=AC%20%3D%20AB%20%2B%20BC)
We know this since the distance of going from A to C (AC) is the same as going from A to B (AB), then B to C (BC).
<h2>2. AB = BC</h2>
The distance of AB is the same as AC.
![AB = BC](https://tex.z-dn.net/?f=AB%20%3D%20BC)
We know this since B is in the middle of AC, so the distance from B to A (BA) is the same as the distance from B to C (BC).
You can see the attached image (at the bottom) for a visualization of this.
<h2>Putting them together</h2>
Since we know the values of AB and BC...
![AB = x+9\\BC = 3x-7](https://tex.z-dn.net/?f=AB%20%3D%20x%2B9%5C%5CBC%20%3D%203x-7)
...we can put these values into our 2nd equation and solve for x:
![AB = BC\\x + 9 = 3x -7](https://tex.z-dn.net/?f=AB%20%3D%20BC%5C%5Cx%20%2B%209%20%3D%203x%20-7)
Add 7 to both sides:
![x + 16 = 3x](https://tex.z-dn.net/?f=x%20%2B%2016%20%3D%203x)
Subtract x from both sides:
![16 = 2x](https://tex.z-dn.net/?f=16%20%3D%202x)
Divide both sides by 2:
![8 = x\\x = 8](https://tex.z-dn.net/?f=8%20%3D%20x%5C%5Cx%20%3D%208)
Knowing x, we can find the distance of AC using our first equation.
![AC = AB + BC](https://tex.z-dn.net/?f=AC%20%3D%20AB%20%2B%20BC)
Let's put in the values of AB and BC:
![AC = (x+9) + (3x-7)](https://tex.z-dn.net/?f=AC%20%3D%20%28x%2B9%29%20%2B%20%283x-7%29)
Before we put in x = 8, we can simplify this:
![AC = (x+9) + (3x-7)\\AC = x + 9 + 3x -7\\AC = x + 3x + 9 -7\\AC = 4x + 9 - 7\\AC = 4x+2](https://tex.z-dn.net/?f=AC%20%3D%20%28x%2B9%29%20%2B%20%283x-7%29%5C%5CAC%20%3D%20x%20%2B%209%20%2B%203x%20-7%5C%5CAC%20%3D%20x%20%2B%203x%20%2B%209%20-7%5C%5CAC%20%3D%204x%20%2B%209%20-%207%5C%5CAC%20%3D%204x%2B2)
We group x and 3x and add those together. Then we subtract 7 from 9.
With this equation, we can put in x = 8:
![AC = 4x +2\\AC = 4*8 + 2](https://tex.z-dn.net/?f=AC%20%3D%204x%20%2B2%5C%5CAC%20%3D%204%2A8%20%2B%202)
Since 4 * 8 = 32:
![AC = 4 * 8 + 2\\AC = 32 + 2\\AC = 34](https://tex.z-dn.net/?f=AC%20%3D%204%20%2A%208%20%2B%202%5C%5CAC%20%3D%2032%20%2B%202%5C%5CAC%20%3D%2034)
Finally, we have found both x and AC.
<h2>Answer</h2>
x = 8
AC = 34