Suppose Andy's and Ben's marginal benefits (in dollars) from a neighborhood water fountain are given as follows: Andy: MB = 26 - 2Q Ben: MB = 18 - Q where Q denotes the diameter of the fountain to be installed.

Suppose that Q = 15.7m, the marginal benefit of an additional unit of the diameter of the fountain to the society is [Answer] dollars.

Continue with the previous question. Suppose that Q = 6.2m, the marginal benefit of an additional unit of the diameter of the fountain to the society is[Answer]dollars.