From home to school, the older sister has to walk 20 minutes, the younger brother has to walk 30 minutes, and the younger brother walks 5 minutes earlier, how many minutes does it take for the older sister to catch up with the younger brother?
从家到学校，姐姐要走20分钟，弟弟要走30分钟，弟弟早走5分钟，姐姐追上弟弟需要多少分钟？
<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/30) * 5</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) - (1/30)</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">(1/6) / (1/60)</gadget>
<output>10</output>

<result>10</result>