A photo is 10 cm long and 6 cm wide. If this photo is enlarged at a ratio of 3:1, what is the area of the enlarged photo?
一张照片长10厘米，宽6厘米．如果按3：1的比把这张照片放大，放大后照片的面积是多少？
<gadget id="calculator">10 * 3</gadget>
<output>30</output>

<gadget id="calculator">6 * 3</gadget>
<output>18</output>

<gadget id="calculator">30 * 18</gadget>
<output>540</output>

<result>540</result>