There are several apples and pears, and the number of apples is three times the number of pears. If you eat 4 apples and 2 pears every day, and there are 20 apples left when the pears are finished, how many pears are there?
有若干个苹果和梨，苹果的个数是梨的个数的3倍．如果每天吃4个苹果和2个梨，梨吃完时还剩20个苹果，梨有多少个？
<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

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

<gadget id="calculator">(3/4) - (1/2)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">5 / (1/4)</gadget>
<output>20</output>

<result>20</result>