Bob wants to create two pens, as shown in the figure. one pen if for a garden and it needs a heavy duty fence to keep out the critters. this heavy duty fence costs $24 per foot. the dog pen shares a side with the garden and has a lighter weight fence on the other three sides that costs $6 per foot. if each pen is to have an area of 1,440, find the values of x and y that would minimize the total cost of the fencing.