Bernstein owns a lot and wants to build a house according to a particular set of plans and specifications. She solicits bids from building contractors and receives three bids: one from Carlton for $160,000, one from Friend for $158,000, and one from Shade for $153,000. She accepts Shade’s bid. One month after beginning construction of the house, Shade contacts Bernstein and informs her that because of inflation and a recent price hike for materials, he will not finish the house unless Bernstein agrees to pay an extra $13,000.Bernstein reluctantly agrees to pay the additional sum. After the house is finished, however, Bernstein refuses to pay the extra $13,000. Discuss whether Bernstein is legally required to pay this additional amount.