in the quantity price contract example in 15.3 we noted that the order quantity Q = 20 is efficient. we can demonstrate that seemingly reasonable contracting method can lead to inefficient results too little output being produced and sold. as before let benefits and cost be B=3Q-Q2/20 and C=Q2/40 respectively. each side knows the others benefit or cost function. the contracting method is as follows:the seller names a price for its output, and the buyer choose the quantity to purchase