A batch of books is distributed to the sixth grade (1/5), and the rest are distributed to the third, fourth, and fifth grades according to the ratio of 3:4:5, and 40 books are allocated to the fifth grade. How many books are there in this batch?
一批图书，分给六年级(1/5)后，其余的按3：4：5的比分给三、四、五年级，五年分得40本，这批图书共有多少本．
<gadget id="calculator">3 + 4 + 5</gadget>
<output>12</output>

<gadget id="calculator">5 / 12</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">40 / (5/12) / (4/5)</gadget>
<output>120</output>

<result>120</result>