So the slope k = (2-1)/(-1-3) =-1/4.

Because the area of triangle CEF is 65438+ 0/4 of the area of triangle ABC.

So CF/CB=CE/CA= 1/2.

Therefore, e and f are the midpoint of AC and AB.

That is, e (3/2,-1/2) f (7/2,-1).

So l: y+1/2 =-1/4 (x-3/2) = > 2x+8y+1= 0.