A rectangle is 20 cm long. If the length is increased by 5 cm, the width remains the same, and the area is increased by 30 cm2. What is the area of the rectangle in cm2?
一个长方形，长20厘米，如果长增加5厘米，宽不变，面积增加30平方厘米，原来这个长方形的面积是多少平方厘米．
<gadget id="calculator">30 / 5</gadget>
<output>6</output>

<gadget id="calculator">20 * 6</gadget>
<output>120</output>

<result>120</result>