1. prove mathematically that MC does not depend on TFC
2. if the average cost of producing 8 units of output in $80 and that of prodcuing 9 units of output is $90, find the marginal cost of the 9th unit of output and the total cost of the last unit
2. if the average cost of producing 8 units of output in $80 and that of prodcuing 9 units of output is $90, find the marginal cost of the 9th unit of output and the total cost of the last unit