The school has 48 literature and art books, and 15 story books are twice as many as literature and art books. How many story books are there?
学校有文艺书48本，故事书比文艺书的2倍少15本，故事书有多少本？
<gadget id="calculator">48 * 2</gadget>
<output>96</output>

<gadget id="calculator">96 - 15</gadget>
<output>81</output>

<result>81</result>