assuming linear.
if k is at (3,4) and j is at (-8,7)
set. (y1,x1) and(y2,x2)
[(y2-y1),(x2-x1)]
[(-8-3),(7-4)]
distance from k to j is (-11,3)
now take coordinates of j and distance from. k->j and add them to get coordinate for L
[(-11+(-8)),(7+3)]= (-19,10)=L