Question

field will be made in the shape of a rectangle with an area of 500 square meters. One side of the field is along a river. A fence will be built along the other three sides. The field will be divided in half by a brick wall which starts at the river. The wall costs $15 per meter and the fence costs $5 per meter. (a) Express the total cost to build this field, including the wall and all fences, in terms of
one single variable. (b) What is the lowest possible cost to build such a field?