HMT, already in the business of marketing agricultural products, decided to try its hand at marketing potatoes for processing. Nine months before the potato harvest, HMT contracted to supply Bell Brand with one hundred thousand sacks of potatoes. At harvest time, Bell Brand would accept only sixty thousand sacks. HMT sues for breach of contract. Bell Brand argues that custom and usage in marketing processing potatoes allows buyers to give estimates in contracts, not fixed quantities, because the contracts are established so far in advance. HMT responds that the quantity term in the contract was definite and unambiguous. Can custom and trade usage be used to interpret an unambiguous contract? Discuss.