Postal rule question.
Danny wrote a letter to Kate offering to sell her his car for $60,000 on August 5. Danny stated in his letter that Kate had to reply by August 15 or he might sell the car to someone else.
On receiving the offer on August 8, Kate immediately sent a letter to Danny asking whether he would accept the price in instalments over ten months. Kate received no reply from Danny and she then posted another letter to Danny accepting his offer on August 14. Danny assumed that Kate did not accept the offer and he sold the car to Lily on August 16. Danny finally received Kate's letter of acceptance on August 17