4. Fred Farmer agrees to sell three tons of wheat stored in one of his silos to Betty Buyer. Under the terms of the contract, the wheat is to be delivered in three months, but Betty agrees to pay 50% of the sales price at the current market rate in 30 days, with the remaining 50% price payable upon delivery at the then-prevalent market rate. A week after entering into the contract, a fire erupts in the grain silo containing the wheat, and 20% of the wheat is completely de-stroyed before the fire is put out. In addition, another 30% of the wheat is damaged by the fire (but is still marketable at a reduced price), and 50% of the wheat is unaffected. When Fred informs Betty of the loss, what are her rights with regard to the contract?