A piece of rectangular colored paper is 20cm long and 15cm wide. First cut out the largest square, and then cut out the largest square from the remaining paper. What is the length of the remaining rectangular piece of paper in cm?
一张长方形彩纸长20cm，宽15cm，先剪下一个最大的正方形，再从余下的纸上剪下一个最大的正方形．这时剩下的长方形纸片的长是多少cm
<gadget id="calculator">20 - 15</gadget>
<output>5</output>

<gadget id="calculator">15 - 5</gadget>
<output>10</output>

<result>10</result>