Write a system of equations to describe the situation below, solve using elimination, and fill in the blanks. Florence likes to knit hats and mittens for friends and family. Last fall, she knitted 3 hats and 4 pairs of mittens, which took a total of 77 hours. This fall, she knitted 3 hats and 3 pairs of mittens, which took a total of 63 hours. If each hat and each pair of mittens takes the same amount of time to knit, how long does it take Florence to knit a hat and a pair of mittens?