The teacher wants to buy pencils. Since the price of pencils has been reduced by 20%, he buys 6 more pencils. The cost remains the same. How much does the teacher plan to buy?
老师要买铅笔，由于铅笔降价20%，所以多买了6支，花的钱不变，老师计划买多少．
<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">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">6 / (1/4)</gadget>
<output>24</output>

<result>24</result>