If 6x+2x=56, what is the value of 4x-7.2?
如果6x+2x=56，那么4x-7.2的值是多少．
<gadget id="calculator">6 + 2</gadget>
<output>8</output>

<gadget id="calculator">56 / 8</gadget>
<output>7</output>

<gadget id="calculator">4 * 7</gadget>
<output>28</output>

<gadget id="calculator">28 - 7.2</gadget>
<output>20.8</output>

<result>20.8</result>