The ratio of A and B is 2:5. The difference between B and A is 10.5. What is B?
甲乙两数的比是2：5，乙数与甲数的差是10.5，乙数是多少．
<gadget id="calculator">5 - 2</gadget>
<output>3</output>

<gadget id="calculator">10.5 / 3</gadget>
<output>3.5</output>

<gadget id="calculator">3.5 * 5</gadget>
<output>17.5</output>

<result>17.5</result>