Question $6$ without completing the additional work, for $$3800.$ What should he do$"?$

a$.$ He should sell the car now for $$3800.$

b$.$ He should keep the car since it wouldn $$ t be rational to spend $$6400$ restoring a car and then sell it for only $$6200.$

c$.$ It does not matter if Bill sells the car now or completes the work and then sells it at the higher price because the outcome will be the same either way

d$.$ He should complete the additional work and sell the car for $$6200.$