A passenger car is driving from A to B, and 20% of the passengers get off on the way, and 10 passengers get on again. At this time, there are more passengers in the car than before (1/20), how many passengers were there in the car?
一辆客车从甲地开往乙地，中途下去乘客的20%，又上来乘客10人．这时车里乘客比原来多(1/20)，车里原来有乘客多少人？
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">1 + (1/20)</gadget>
<output>21/20 = around 1.05</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(21/20) - (4/5)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">10 / (1/4)</gadget>
<output>40</output>

<result>40</result>