A math problem, 20 people in the class get it right and 5 people get it wrong, what is the error rate of this problem?
一道数学题，全班20人做对，5人做错，这道题的错误率是多少．
<gadget id="calculator">20 + 5</gadget>
<output>25</output>

<gadget id="calculator">5 / 25</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">100 / 100</gadget>
<output>1</output>

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

<result>1/5 = around 0.2</result>