P - q i believe because
p = total average
q = average of ac
x = average of bd
p - q = x
Answer:
BD - AC = 0
Step-by-step explanation:
Given that:
BC = 36 , CD = 15 and BD = x
As these are forming right angled triangle,
Using Pythagorean theorem,

Taking square root on both sides

As the given shape is rectangular, the sides parallel to each other will have same values.
AB = 15 , AD = 36 and AC = x

Now,
BD - AC = 39 - 39 = 0
Hence,
BD - AC = 0
I got D. When looking at the point where they intersect is -4, and 2 1/2. hope I helped the best I could