The ratio of the two numbers of A and B is 2:5, the number of A is 4, what is the number of B.
甲乙两个数的比是2：5，甲数是4，乙数是多少．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">4 / (2/5)</gadget>
<output>10</output>

<result>10</result>