If 5x+1=7.5, then 6x-1=how much
如果5x+1=7.5，那么6x-1=多少
<gadget id="calculator">7.5 - 1</gadget>
<output>6.5</output>

<gadget id="calculator">6.5 / 5</gadget>
<output>1.3</output>

<gadget id="calculator">6 * 1.3</gadget>
<output>7.8</output>

<gadget id="calculator">7.8 - 1</gadget>
<output>6.8</output>

<result>6.8</result>