The school bought 165 science books, 21 less than three times the number of story books. How many story books did you buy?
学校买来165本科技书，科技书的本数比故事书的3倍少21本．买来故事书多少本？
<gadget id="calculator">165 + 21</gadget>
<output>186</output>

<gadget id="calculator">186 / 3</gadget>
<output>62</output>

<result>62</result>