The number of A is 20, and the number of B is 15. How much less is the number of B than the number of A?
甲数是20，乙数是15，乙数比甲数少几分之几？
<gadget id="calculator">20 - 15</gadget>
<output>5</output>

<gadget id="calculator">5 / 20</gadget>
<output>1/4 = around 0.25</output>

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