At the fair, a book was sold at a 50% discount, but it cost 16.5 yuan. Do you know the original price?
在展销会上，一本书打5折出售，结果花16.5元就买到了，你知道原价吗？
<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">16.5 / (1/2)</gadget>
<output>33</output>

<result>33</result>