June 14 (Reuters) - Real estate developer Group Mach Inc said on Friday it had submitted a formal offer for Canadian travel operator Transat AT Inc TRZ.TO on Thursday. had said earlier this month it would take Transat private at C$14 per share in cash, C$1 more than Air Canada 's AC.TO all-cash offer that valued the parent company of leisure carrier Air Transat at C$520 million.