Hello!!
We know y = 7 + x. Substitute this into our other equation,
2x = (x + 7) - 10
2x = x - 3
x = -3
Now, we know that x = -3 so, we can conclude that the answer is choice B.
Hope this helps!! Let me know if you have ANY questions.
Answer:

Step-by-step explanation:
Given
4 and 5
Required
Determine the halfway
This is calculated as:


Remove bracket


There you go! Hope this helps