Suppose that a small company is thinking of putting plants in their lobby for employees to view and enjoy. since the plants are to be viewed by employees, the plants are non-excludable (it is infeasible to move a plant each time a specific individual walks by) and non-rival in consumption (if one worker looks at the plant, it does not prevent another from doing so as well). the company employs three workers: tim, greg, and sharon. the company is thinking about buying up to three plants, and wants to know how much workers would enjoy each plant. for tim, the first plant has a benefit of $ 47 per day, the second plant has a benefit of $ 37 per day, and the third plant has a benefit of $ 13 per day. for greg, the first plant has a benefit of $ 41 per day, the second has a benefit of $ 28 per day, and the third has a benefit of $ 6 per day. for sharon, the first plant has a benefit of $ 31 per day, the second has a benefit of $ 19 per day, and the third has a benefit of $ 2 per day. given that no one else will see the plants, no one else values the plants in the lobby. what is the marginal social benefit of the first plant?