The school library purchased 300 story books, 50 more than twice the number of science and technology books. How many technical books should I buy?
学校图书室购进300本故事书，比科技书的2倍多50本．购进科技书多少本？
<gadget id="calculator">300 - 50</gadget>
<output>250</output>

<gadget id="calculator">250 / 2</gadget>
<output>125</output>

<result>125</result>