 In the simple two-by-two case, let us assume that \(r_{\textrm{Bob}} = r_{\textrm{Sally}} = 100\) and that \(c = 150,\) so that the efficiency condition is satisfied. If either Bob or Sally buy the public good, but not both, they would have to be charged the full cost, leading to an outcome of \(-50.\) The not-buying individual will free-ride on the other’s contribution and get 100. If both contribute, each receives a benefit \(100 - 150/2 = 25.\) If neither contributes, the good will not be produced and both end up with zero. The payoffs are displayed in the matrix in Table 2.