After a basket of apples is sold (1/5), another 9 kilograms are sold, which is exactly half of the total. How many kilograms does this basket of apples originally have?
一筐苹果卖掉(1/5)后，又卖掉9千克，这时正好卖出总数的一半，这筐苹果原来有多少千克？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">(1/2) - (1/5)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">9 / (3/10)</gadget>
<output>30</output>

<result>30</result>