The current profit for a subunit is N$36,000. Its current invested capital is N$200,000. The subunit is considering purchasing for $20,000 equipment that will increase annual profit by an estimated N$2,800. The firm's cost of capital is 12%. If the equipment is purchased, what will be the increase in residual income of the subunit? a. 4% b. N$2,800 c. N$16,000 d. N$400