If the width of a rectangle is increased by 3 times, the area will increase by 18 square centimeters. At this time, it is just a square. What is the area of the original rectangle in square centimeters?
一个长方形的宽如果增加3倍，面积就增加18平方厘米，这时刚好是一个正方形，原来长方形的面积是多少平方厘米．
<gadget id="calculator">18 / 12</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">4 * (3/2)</gadget>
<output>6</output>

<result>6</result>