A number plus its 2.5 times is 10.5, what is this number?
一个数加上它的2.5倍是10.5，这个数是多少．
<gadget id="calculator">2.5 + 1</gadget>
<output>3.5</output>

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

<result>3</result>