(2/7) of a rectangular paper is painted blue, (3/7) is painted red, what percentage of the paper is the unpainted part?
一张长方形纸的(2/7)涂蓝色，(3/7)涂红色，没有涂色的部分占这张纸的几分之几？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 - (2/7) - (3/7)</gadget>
<output>2/7 = around 0.285714</output>

<result>2/7 = around 0.285714</result>