A farmer wishes to fence a rectangular pasture of area $2800~m^2$. One side of the fence is along a road, and that side costs \$5 per meter. The other 3 sides cost \$2 per meter.
Find the minimum possible cost.
I would be able to do this if all of the sides cost the same, but the fact that the one side costs \$5 throws me off. I understand that the formula will be $xy = 2800$. But I do not know how to represent the variables and isolate them.
Any help is much appreciated!