A rancher wants to build a fence to enclose an 1800 square meter rectangular field for cattle. the fence along one side is to be made of heavy-duty material that costs $12 per meter. the material along the remaining three sides costs only $7 per meter. find the dimensions and total cost of fencing the field that is the least expensive to fence.?

At the county fair, animals are judged for the quality of their breeding and health. the animal pens are arranged in an array, with one animal in each pen. a barn can hold at most 10 rows of pens and at most 6 pens in each row, with room for people to walk around them. what different ways can the planners of the county fair arrange the pens for the horses and cows in the same barn?