There are 620 story books and science books in the school library, and the number of story books is three times that of science books. How many story books are there?
学校图书室有故事书和科技书共620本，故事书的本数是科技书的3倍．故事书有多少本．
<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<gadget id="calculator">620 / 4</gadget>
<output>155</output>

<gadget id="calculator">155 * 3</gadget>
<output>465</output>

<result>465</result>