Bill, bob, and barry are hired to paint signs. in 8 hours bill can paint 1 sign, bob can paint 2 signs, and barry can paint 1 and 1/3 signs. they all come to work the first day, but barry doesn't like the job and quits after 3 hours. bob works half an hour longer than barry and quits. how long will it take bill to finish 2 signs they were supposed to paint?