The distance between A and B is 6 kilometers. A person travels from A to B. He travels an average of 80 meters per minute in the first half of the time, and 70 meters per minute in the second half of the time. How long does it take him to complete the journey?
甲乙两地相距6千米，某人从甲地去乙地，此人前一半时间平均每分钟行80米，后一半时间平均每分钟行70米，他行完路程用了几分钟？
<gadget id="calculator">6 * 1_000</gadget>
<output>6_000</output>

<gadget id="calculator">80 * 0.5</gadget>
<output>40</output>

<gadget id="calculator">70 * 0.5</gadget>
<output>35</output>

<gadget id="calculator">40 + 35</gadget>
<output>75</output>

<gadget id="calculator">6_000 / 75</gadget>
<output>80</output>

<result>80</result>