The library bought 240 science and technology books, 20 more than 40% of the literary books bought. How many literary books were bought?
图书室买来240本科技书，比买来的文艺书的40%多20本，买来文艺书多少本？
<gadget id="calculator">240 - 20</gadget>
<output>220</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">220 / (2/5)</gadget>
<output>550</output>

<result>550</result>