It’s c you add the exponents
Answer:

Step-by-step explanation:
We have been given the intersection coordinates:
(7,1,-6) and perpendicular to the line x=-1+t ,y=-2+t and z=-1+t
From the condition of perpendicularity we know:


Now, we have given x=-1+t , y=-2+t and z= -1+t





Now, substituting t in the given coordinates x,y and z we get:


And 
4x = x + 15
Hope this helps you! Hope your thanksgiving goes well, here's a turkey!