Find the dimensions that uses the least amount of fencing.?

A farmer wishes to build a large rectangular grazing area of dimensions, width, and length, splitting the area in to 4 equal fields by dividing the width into 4 equal pieces. The total area of all the fields must be 11000 square feet. Find the dimensions that uses the least amount of fencing. Please help me with this question i'm starting to do: A= 11000 , F= 2L+5W, A=LW,so, LW=11000, L=11000/W,i replaced L in F: 2(11000/W)+5W, tride to find derivative but i stack.