Xiao Ming has 21 story books, which belong to Xiao Gang (3/5). How many story books does Xiao Gang have?
小明有故事书21本，是小刚的(3/5)，小刚有故事书多少本．
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">21 / (3/5)</gadget>
<output>35</output>

<result>35</result>