Yummy Biscuits and Speedy Mart (a chain of 100 supermarkets) enter a contract where the biscuit-making company will supply 1,000 biscuit packs a day at $50 per pack to Speedy Mart for the next six months. However, Yummy Biscuits stops their supplies to Speedy Mart mid-way, claiming that the prices of each biscuit pack, due to severe inflation, are $80. If Yummy continued to deliver at $50, it would lose $20 per biscuit pack it delivered. Speedy Mart sues Yummy, saying that it has to oblige by the contract signed. Evaluate the case.