The length of a rectangle is 21 meters and the width is 6 meters. If the width increases by 50 decimeters, how many square meters does the area increase?
一个长方形的长是21米，宽是6米，如果宽增加50分米，则面积增加多少平方米？
<gadget id="calculator">50 / 10</gadget>
<output>5</output>

<gadget id="calculator">21 * 5</gadget>
<output>105</output>

<result>105</result>