The school purchased a new batch of books and allocated them to grades four, five, and six according to the ratio of 4:5:8. It is known that the fifth grade has 60 books less than the sixth grade. How many books are allocated to the fourth grade?
学校新购进一批图书，分别按4：5：8的比例分配给四、五、六三个年级，已知五年级比六年级少60本，四年级分到了多少本图书？
<gadget id="calculator">8 - 5</gadget>
<output>3</output>

<gadget id="calculator">60 / 3</gadget>
<output>20</output>

<gadget id="calculator">20 * 4</gadget>
<output>80</output>

<result>80</result>