plz explain all the steps ..

(5) Each individual's preferences can be represented by the utility function 15(x + 1) + y;. When 1 unit of Y is used as input exactly one-third of a unit of X is obtained as output. (A) What is the marginal social cost of X? (B) Can an allocation for which x = 9 be efficient if each individual has a positive amount of the private good? If so, explain why, if not, prove it with a numerical example. (C) Can an allocation for which x = 29 be efficient? If so, explain why; if not, prove it with a numerical example. (5) Each individual's preferences can be represented by the utility function 15(x + 1) + y;. When 1 unit of Y is used as input exactly one-third of a unit of X is obtained as output. (A) What is the marginal social cost of X? (B) Can an allocation for which x = 9 be efficient if each individual has a positive amount of the private good? If so, explain why, if not, prove it with a numerical example. (C) Can an allocation for which x = 29 be efficient? If so, explain why; if not, prove it with a numerical example