The number that belongs in the blank space is answer choice A. 6
Answer:
13
Step-by-step explanation:
they go at diffrent speed of electric.
Since you don't provide the coordinates of the point W, I will help you in a general form anyway. In the Figure below is represented the segment that matches this problem. We have two endpoints U and V. So, by using the midpoint formula we may solve this problem:

Therefore:

So we know
but we also must know 
Finally, knowing the points U and W we can find the endpoint V.
Multiply both sides of the second equation by 4. That will give you -4x in the second equation which when added to 4x of the first equation will eliminate x.
Second equation:
-x + 3y = 6
Multiply the second equation by 4 on both sides:
-4x + 12y = 26