Two girder designs are under consideration for a bridge for a 1,200-foot crossing. The first is expected to result in a superstructure weight per foot of 22(S)+800, where S is the span between piers. The second should result in superstructure weight per foot of 20(S) +1,000. Piers and two required abutments are estimated to cost $220,000 each. The superstructure will be erected at a cost of %5.40 per pound. Choose the girder design that will result in a minimum cost and specify the optimum number of piers.