Honghong got 5 questions wrong and got 15 questions right, what is the error rate?
红红做错了5道题，做对了15道题，差错率是多少．
<gadget id="calculator">5 + 15</gadget>
<output>20</output>

<gadget id="calculator">5 / 20</gadget>
<output>1/4 = around 0.25</output>

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

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

<result>1/4 = around 0.25</result>