Answer Happy

Can i get some detailed explanation for this question?
There is a small country A with its domestic demand (D) and supply (S) for product Y being D=120-P and S = P where P denotes the price of product Y in country A. The international price of product Y is $20. An economist claims that the government of Country A imposes such a quota because of its political consideration. More specifically, the economist argues that the government values the producer surplus a times higher than the consumer surplus and the quota revenue. If the government were setting the import quota at 40 units in order to maximize its political objective function as claimed by the economist, then what should have been the value for d? a=