Answer 1: 31 years old
Answer 2: 7(3+3/7)
Answer 3: 2 pounds 7 shillings and sixpence.
Answer 4: 7.5 degrees
Answer 5: Start the two timers together. When the 4 minute timer is empty there is 3 minutes left in the 7-minute timer. Then start the cooking and turn over both timers. When that 3 minutes (in the 7 minute timer) is up there is 1 minute left in the 4-minute timer. (This is the first 3 minutes). Turn them both over and there is 3 minutes left in the 4 minute timer and 7 minutes left in the other. When the 4 minute timer is empty (second 3 minutes has elapsed) there is 3 minutes elapsed in the 7-minute timer. Turn this over to measure the last 3 minutes!