The Smurfs set off from home every day and come back to fetch water from the river. It can walk 5 meters per minute when carrying an empty bucket, and 3 meters per minute when carrying a full bucket. The Smurf is 30 meters away from the river, so how many minutes does it take him to fetch a bucket of water from home?
蓝精灵每天从家出发，到河边打水回来．它提空桶时每分钟能走5米，提一个装满水的桶时每分钟能走3米．蓝精灵离河边有30米，那么他从家出发打一桶水，来回一趟共需多少分钟？
<gadget id="calculator">30 / 5</gadget>
<output>6</output>

<gadget id="calculator">30 / 3</gadget>
<output>10</output>

<gadget id="calculator">6 + 10</gadget>
<output>16</output>

<result>16</result>