Cindy has 38 meters of fencing. she plans to fence in a rectangular dog run that is 4 meters wide. how long can the ride me made?

I just answered this question my self for plato.  

38=2L+2(4)

38=2L  

15=L

fist on the left goes with the third on the right. second on the left goes with the fourth on the right. third on the left goes with the second on the right. the fourth on the left goes with first on the right