The bookstore shipped a batch of new books, sold them on the first day (3/7), sold 100 copies on the second day, and left 60 books. How many books are there in total?
书店运到一批新书，第一天卖出(3/7)，第二天又卖出100本，还剩60本，这批书一共多少本？
<gadget id="calculator">100 + 60</gadget>
<output>160</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 - (3/7)</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">160 / (4/7)</gadget>
<output>280</output>

<result>280</result>