Little Ding Ding reads a 320-page story book. On the first day, he reads 45 pages. From the second day on, he reads 50 pages every day. On the fifth day, which page should he start to read?
小丁丁看一本320页的故事书，第一天看了45页，从第二天起每天都看50页，到了第五天应从第几页开始看？
<gadget id="calculator">50 * 3</gadget>
<output>150</output>

<gadget id="calculator">45 + 150 + 1</gadget>
<output>196</output>

<result>196</result>