If the length and width of a rectangle are increased by 10 cm, the area of the new rectangle is 400 cm2 larger than the area of the original rectangle. What is the perimeter of the original rectangle in cm?
一个长方形的长和宽都增加10厘米，形成的新长方形面积比原长方形的面积大400平方厘米，原来长方形的周长是多少厘米．
<gadget id="calculator">30 * 2</gadget>
<output>60</output>

<result>60</result>