A ship sails at the same speed, it takes 3 days to travel from city A to city B, and 4 days to travel from city B to city A. How many days does it take for a drift bottle to go from city A to city B?
轮船以相同速度航行，从A城到B城需3天，从B城到A城需4天．一个漂流瓶从A城到B城需几天？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/3) - (1/4)</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/12) / 2</gadget>
<output>1/24 = around 0.041667</output>

<gadget id="calculator">1 / (1/24)</gadget>
<output>24</output>

<result>24</result>