After a basket of pears is sold (2/5), the weight of the basket is 20kg, and after (1/2) is sold, the weight of the basket is 17kg. How many kilograms does the basket of pears weigh?
一筐梨卖出(2/5)后，连筐重20kg，卖出(1/2)后，连筐重17kg，这筐梨原来有多少千克？
<gadget id="calculator">20 - 17</gadget>
<output>3</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(1/2) - (2/5)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">3 / (1/10)</gadget>
<output>30</output>

<result>30</result>