Xiao Ming reads a story book. On the first day, he reads 60 pages. On the second day, the number of pages he reads is 20 pages less than that of the first day. On the third day, the number of pages he reads is the sum of the previous two days. From which page does the day start?
小明看一本故事书，第一天看了60页，第二天看的页数比第一天得2倍少20页，第三天看的页数是前两天的总和，小明第四天从第几页看起？
<gadget id="calculator">60 * 2</gadget>
<output>120</output>

<gadget id="calculator">120 - 20</gadget>
<output>100</output>

<gadget id="calculator">60 + 100</gadget>
<output>160</output>

<gadget id="calculator">60 + 100 + 160 + 1</gadget>
<output>321</output>

<result>321</result>