A rectangular playground is 15 meters long. If the length is increased by 5 meters and the width is decreased by 3 meters, then the current area is the same as before. What is the original area of the playground?
一个长方形操场长15米，如果长增加5米，宽减少3米，那么现在的面积和原来一样大．这个操场原来的面积是多少平方米？
<gadget id="calculator">15 * 3</gadget>
<output>45</output>

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

<gadget id="calculator">45 + 15</gadget>
<output>60</output>

<gadget id="calculator">5 - 15</gadget>
<output>-10</output>

<gadget id="calculator">15 + (-10)</gadget>
<output>5</output>

<gadget id="calculator">60 / 5</gadget>
<output>12</output>

<gadget id="calculator">15 * 12</gadget>
<output>180</output>

<result>180</result>