For a rectangle, if its length increases by 3 centimeters, its area will increase by 15 square centimeters. If its width decreases by 2 centimeters, its area will decrease by 18 centimeters. Find the area of the original rectangle?
一个长方形，若它的长增加3厘米面积就增加15平方厘米，若它的宽减少2厘米，面积就减少18厘米，求原长方形的面积？
<gadget id="calculator">18 / 2</gadget>
<output>9</output>

<gadget id="calculator">15 / 3</gadget>
<output>5</output>

<gadget id="calculator">9 * 5</gadget>
<output>45</output>

<result>45</result>