The school books bought 900 books, including 550 story books, and the rest were science and technology books. How many fewer science and technology books than story books?
学校图书买来900本书，其中故事书550本，剩余的是科技书，科技书比故事书少多少本？
<gadget id="calculator">900 - 550</gadget>
<output>350</output>

<gadget id="calculator">550 - 350</gadget>
<output>200</output>

<result>200</result>