Xiao Ming bought a set of "The Complete Works of Andersen's Fairy Tales" and paid 68 yuan, which is 20% off the original price. How much is the original price of this set of books? (solution by equation)
小明买了一套《安徒生童话全集》，付了68元，比原价优惠了20%，这套书原价多少元？(用方程解)
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">68 / (4/5)</gadget>
<output>85</output>

<result>85</result>