The library of Aida Primary School bought 156 more literature and art books than science and technology books, and the number of literature and art books was 2 times more than that of science and technology books. How many science and technology books did you buy?
爱达小学的图书馆买的文艺书比科技书多156本，文艺书的本数比科技书的3倍还多2本，科技书买了多少本？
<gadget id="calculator">156 - 2</gadget>
<output>154</output>

<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">154 / 2</gadget>
<output>77</output>

<result>77</result>