10. Xiao Ming and Xiao Qiang have the same number of chocolates. They start eating at the same time. Xiao Ming eats 1 piece every 20 minutes and finishes the last piece at 14:40; Xiao Qiang eats 1 piece every 30 minutes and finishes the last piece at 18:00. Then, they started eating their first piece of chocolate at $\qquad$ o'clock.
Answer: 8