The school purchased a batch of books and lent them to grades four, five and six according to the ratio of 2:3:5. How many of these books have been borrowed in the fourth grade?
学校购到一批书，按2：3：5借给四、五、六三个年级．四年级借到这批书的多少．
<gadget id="calculator">2 + 3 + 5</gadget>
<output>10</output>

<gadget id="calculator">2 / 10</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>