2.5:5=x:10, then in x:3=a:0.4, what is the value of a.
2.5：5=x：10，则x：3=a：0.4中，a的值是多少．
<gadget id="calculator">5 * 0.4</gadget>
<output>2</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<result>2/3 = around 0.666667</result>