The length of a rectangle is a meter and the width is 0.1 meters less than the length. What is the area of the rectangle?
一个长方形的长是a米，宽比长少0.1米，这个长方形的面积是多少．
<gadget id="calculator">2 - 0.1</gadget>
<output>1.9</output>

<result>1.9</result>