Davidson Farms was in the business of growing and selling farm products. It decided to expand its business by growing and selling potatoes. Ten months before the potato harvest, Davidson entered into a contract to sell to Safeway Stores 100,000 sacks of potatoes. Following the harvest, Safeway accepted 60,000 sacks and refused the remaining 40,000 sacks. Davidson sued citing breach of contract. Safeway Stores argued that custom and usage in marketing processing potatoes allows buyers to give estimates in contracts, not fixed quantities, especially in situations where the contracts are established so far in advance. Davidson responded by indicating that the quantity of potato to be purchased was clear and definite. Can custom and trade usage be used to interpret an unambiguous contract? Discuss.