After a library has lent out 1200 books, the remaining part is 300 less than the original number (3/4). How many books are there in this library?
一个图书室借出1200本书后，剩下的部分比原来本数的(3/4)少300本，这个图书馆原有书多少本．
<gadget id="calculator">1_200 - 300</gadget>
<output>900</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">900 / (1/4)</gadget>
<output>3_600</output>

<result>3_600</result>