The original price of a volleyball is 60 yuan, how much will it cost after 30% off?
一个排球原价60元，打七折后卖多少元．
<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">60 * (7/10)</gadget>
<output>42</output>

<result>42</result>