A 50′ by 24′ house will have floor joist that are 12′ long and rest on a center beam. The joist are spaced 20″ on center. How many joist are needed?

A 50′ by 24′ house will have floor joist that are 12′ long and rest on a center beam. The joist are spaced 20″ on center. How many joist are needed?