Deal-a-day coupon company Groupon and online travel company Expedia Inc. said Wednesday they will launch a new travel website together. The companies say they’ll offer discounts on hotels, airline tickets, car rentals, cruises and vacation activities. The deals will follow the Groupon model, where customers have a limited time to buy a voucher that they can then redeem at a later date.The companies say that discounts will be significant – about 50 percent off retail rates found at other online travel sites, they said.The website, to be called Groupon Getaways with Expedia, is expected to launch late this month.Shares of Expedia, based in Bellevue, Wash., lost 21 cents to close at $27.80 in a widely falling market. Groupon is based in Chicago.