(3/9) of a piece of rectangular paper is painted red, and (2/5) is painted blue. What fraction of the paper is not colored?
一张长方形纸的(3/9)涂红色，(2/5)涂蓝色．没涂色部分占这张纸的几分之几？
<gadget id="calculator">3 / 9</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(1/3) + (2/5)</gadget>
<output>11/15 = around 0.733333</output>

<gadget id="calculator">1 - (11/15)</gadget>
<output>4/15 = around 0.266667</output>

<result>4/15 = around 0.266667</result>