The 20% discount for a storybook is 20 yuan. What is the original price of this storybook?
一本故事书八折优惠是20元，这本故事书的原价是多少元．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">20 / (4/5)</gadget>
<output>25</output>

<result>25</result>