Column calculation: the number 0.5 more than twice x is (6/7), find x.
列式计算：比x的2倍多0.5的数是(6/7)，求x．
<gadget id="calculator">6 / 7</gadget>
<output>6/7 = around 0.857143</output>

<gadget id="calculator">(6/7) - 0.5</gadget>
<output>0.357143</output>

<gadget id="calculator">0.357143 / 2</gadget>
<output>0.178571</output>

<result>0.178571</result>