Answer:
Hello!!! Princess Sakura here ^^
Explanation:
If you take a look you can see that the whole line is 17..um....units. The 2x-4 and the 2x-7 are together on the line is if you add them together you should end up with 17 units.
So the value of x is 7, but if you wanted to know what each line measures you'll have to plug it in. For example line AB will measure 10 units.