After a 35% discount on a schoolbag, it is 21 yuan cheaper than before. How much is the original price of this schoolbag?
一个书包打六五折后，比原来便宜21元．这个书包原价多少元？
<gadget id="calculator">65 / 100</gadget>
<output>13/20 = around 0.65</output>

<gadget id="calculator">1 - (13/20)</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">21 / (7/20)</gadget>
<output>60</output>

<result>60</result>