Starting from Children's Day, Xiao Ming read 80 pages of books in the first 4 days. According to this calculation, how many pages can Xiao Ming read in total this month? (Solution with proportional knowledge)
从"六一"儿童节那天开始，小明前4天看了80页书，照这样计算，这个月小明一共可以看多少页书？(用比例知识解)
<gadget id="calculator">80 / 4</gadget>
<output>20</output>

<gadget id="calculator">20 * 30</gadget>
<output>600</output>

<result>600</result>