There were 40 original books in Class 1, and now they have increased to 50. How many books of books have increased
六1班原有图书40本，现增加到50本．图书的本书增加了多少
<gadget id="calculator">50 - 40</gadget>
<output>10</output>

<gadget id="calculator">10 / 40</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>