It takes 5 hours for a ship to travel from Wuhan to Jiujiang, and 7 hours to travel from Jiujiang to Wuhan. How long does it take for a member of the Yangtze River drifting team to naturally drift from Wuhan to Jiujiang on a raft?
轮船从武汉到九江要行驶5小时，从九江到武汉要行驶7小时，问一长江飘流队员要从武汉乘木筏自然飘流到九江需要多少小时？
<gadget id="calculator">7 * 5</gadget>
<output>35</output>

<result>35</result>