In the xy-coordinate system, if (m,n) and (m+2, n+k) are two points on the line perpendicular to x=2y+5, then k=?  Choose the correct choice from the following answers
A) -5 B) -8 C) 2 D) -4 E) 1
the slope= k/2   the line perpendicular to x=2y+5 or y=1/2x-5/2 has   a slope= -1/ (1/2) =-2 ---&gt;k/2=-2 --&gt; k=-4   Answer is -4
<result>D</result>
In the xy-coordinate system, if (m,n) and (m+2, n+k) are two points on the line perpendicular to x=2y+5, then k=?