Simple operation: (2.5-2.5*0.6)/0.4.
简便运算：(2.5-2.5*0.6)/0.4．
<gadget id="calculator">2.5 * 0.6</gadget>
<output>1.5</output>

<gadget id="calculator">2.5 - 1.5</gadget>
<output>1</output>

<gadget id="calculator">1 / 0.4</gadget>
<output>2.5</output>

<result>2.5</result>