The price of a science fiction novel is 21 yuan at a 25% discount. How much is the original price of this science fiction novel?
一本科幻小说按七五折出售的价格是21元，这本科幻小说原价多少元？
<gadget id="calculator">75 / 100</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">21 / (3/4)</gadget>
<output>28</output>

<result>28</result>