The answer is A. Always for perpendicular you flip the sign and the numbers
The equation of a circle:

(h,k) - the coordinates of the center
r - the radius
The center is the midpoint of the diameter.

The radius is half the diameter, or the distance from one of the endpoints to the center.

The equation of the circle:
Answer:C
Step-by-step explanation:
A.B.C+A.B'.C+A'.B.C+A.B.C'
By distributive law : A.B.C+A.B.C' = A.B(C+C')
By complement law: C+C'=1, so
A.B(C+C')=A.B
Therefore the answer will be A.B'.C+A'.B.C+A.B
The cost for 8 plates would be 72, and I believe it is proportional.
Hope it helps!
9ths answer. 113.112 ~ 113.1