4x+0.7*3=6.5．
4x+0.7*3=6.5．
<gadget id="calculator">0.7 * 3</gadget>
<output>2.1</output>

<gadget id="calculator">6.5 - 2.1</gadget>
<output>4.4</output>

<gadget id="calculator">4.4 / 4</gadget>
<output>1.1</output>

<result>1.1</result>