C and d i think hope it helps
This is called the commutative property (ies).
Search the commutative property of Multiplication, addition, etc...
Solution:
(1) Midpoint:
A point in the middle of the line segment that divides it into two equal parts.
Mid point formula:

Middle of a segment; in the form of a coordinate plane.
(2) Slope:
To find the slope of the line when passing through two points.
Slope formula:

(3) Distance:
To find the distance of two points.
Distance formula:

The measure of an angle = 2 * the compliment of the angle - 15
Angle = 2 * (180 - angle) - 15
x = 2 * 180 - 2 * x - 15
x = 345 - 2x
3x = 345
x = 115 degrees.
I think the answer is 240 :)