Complete the following with example:
MT, 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 100,000 sacks of potatoes. At harvest time, Bell Brand would only accept 60,000 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, since 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.