A passenger car travels from A to B. 30% of the passengers get off on the way, and 12 passengers get on. At this time, the number of passengers in the car is 10% more than before. 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30%，又上来乘客12人，这时车里的乘客比原来多10%，车里原来有乘客多少人？
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 + (1/10)</gadget>
<output>11/10 = around 1.1</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">(11/10) - (4/5)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">12 / (3/10)</gadget>
<output>40</output>

<result>40</result>