The school purchased a batch of books and distributed them to grades four, five, and six according to the ratio of 4:5:6. Grade six got 40 more books than grade four, and how many books did grade five get?
学校购进一批图书，按4：5：6分给四、五、六三个年级，六年级比四年级多分得40本，五年级分得多少本？
<gadget id="calculator">4 - 2</gadget>
<output>2</output>

<gadget id="calculator">40 / 2</gadget>
<output>20</output>

<gadget id="calculator">20 * 5</gadget>
<output>100</output>

<result>100</result>