The city on Tuesday will hold a public bid opening to choose a company to supply furniture and equipment for new science labs at Medford High School. The bids will be opened at 2 p.m. in the purchasing office, Room 105 at City Hall. Medford was one of 10 communities selected by the Massachusetts School Building Authority to participate in a $60 million program to use federal money to upgrade science labs in public high schools. The state will pay 60 percent of the cost in Medford, and the city 40 percent. In September, G & R Construction of Quincy was selected as the general contractor on the project after submitting a bid of $8.4 million, the lowest received by the city.