24. Two trains leave two towns fifty miles apart. They travel toward each other at rates of 30 mph and 20 mph respectively. A bumble bee flying at the rate of 50 mph leaves as the faster train departs the train station and flies to the slower train. The bee then turns around and comes back to meet the faster train. It turns around again and keeps flying back and forth between the trains until the trains meet. How far does the tired bumble bee fly?
① 20 ② 30 ③ 40 ④ 50 ⑤ 60

22. Make a deck of 10 cards, each with one counting number from 1 through 10 on it. (You could use a regular deck of cards letting the Ace be 1.) When they are placed face down, the first card turned up is 1. The second card, still face down, is placed at the bottom of the stack. The new top card (third one in the initial stack) is turned up and it is 2. The next card is placed face down at the bottom of the stack. The next card is turned up and is 3. The process of turning one card up and placing the next on the bottom of the stack is repeated until all cards are face up.
Arrange the stack so they will appear in the proper numerical order when the above directions are followed. Then what is the number written on 4-th card?
① 6 ② 7 ③ 8 ④ 9 ⑤ 10
대강 무슨말인지 해셕은 되겠는데, 확실치가 않아서요 ㅠㅠ
부탁드립니다^^*