A profit-maximizing monopoly has pricing under the following conditions: the price charged for goods produced is $15, the intersection of the marginal-revenue and marginal-cost curves occurs where output is 105 units and marginal revenue is $10, and the socially efficient level of production is 125 units. The demand curve is linear and downward sloping, and the marginal-cost curve is linear and upward sloping. What is the deadweight loss?