Write a linear equation to represent the line shown on the graph

1. J(1,9), K(7,4), L(8,13), M(-2,1)
2J(13,-5), K(2,6), L(-1,-5), M(-4,-2)
3J(-10,-7), K(-4, 1), L(-3, 2), M(-6,-2)
4J(11,-2), K(3,-2), L(1,-7), M(1,-2)

Can someone tell me how to do this