on 10 july ace ltd posted an offer to sell a consignment of 1,000 widgets to brian, a retailer. the offer said that the price was 10,000 and that the offer would remain open until 31 july. on 12 july brian telephoned ace ltd and asked whether he would be allowed three months' credit. ace ltd's manager replied that payment would have to be made in cash, upon delivery. on 29 july ace ltd sold the consignment of widgets to a third party, charles. on 30 july brian posted a letter accepting ace ltd's offer. this letter arrived on 1 august. upon opening the letter, ace ltd's manager telephoned brian and told him that the consignment of widgets had been sold and that further similar widgets were not available. advise the parties as to whether or not a contract has been created