Which expression represents the difference between 2n and 15

Is these the choices to chose from:
A) 2n-15
B) 15-2n
C) Both A and B
D) Neither A nor B

*If so, i think its C*

“exterior angles of triangles. an exterior (or external) angle is the angle between one side of a triangle and the extension of an adjacent side. try this drag the orange dots on any vertex to reshape the triangle.” look to get to the answer i explained what it means and other things i hope it you .