Consider production process that requires an upstream firm A to make an input, transfer to a downstream firm B, who then sells to the final consumer. One unit of input from A is required for one unit of final output. The marginal cost of production for firm A is 20 per unit. B has zero marginal costs. There are zero fixed costs. The final demand curve for end consumers is P = 200 – q. a. What is the proft-maximising level of output, the related price and profit, if A and B work together to maximise joint profit.