A field of rape can produce 20 tons of rape this year, which is 25% more than last year. How many tons more than last year?
一块油菜地，今年产油菜20吨，比去年增产25%，比去年增产多少吨？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">20 / (5/4)</gadget>
<output>16</output>

<gadget id="calculator">20 - 16</gadget>
<output>4</output>

<result>4</result>