(3/7) of a piece of rectangular paper is painted blue, (1/7) is painted red, what is the part of the paper that is not painted.
一张长方形纸的(3/7)涂蓝色，(1/7)涂红色，没有涂色的部分占这张纸的多少．
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">1 - (3/7) - (1/7)</gadget>
<output>3/7 = around 0.428571</output>

<result>3/7 = around 0.428571</result>