The table sets out total benefit of a public good for Wendy, Sara, and Tom, who are only people in the society. Units of Total benefit public good Wendy Sara Tom If the government provides 2 units of the public good, what is the marginal social benefit? 20 10 30 50 60 20 60 80 25 65 5 100 30 67 When the government provides 2 units of the public good, the marginal social benefit is