If a rectangle with a length of 10 cm and a width of 5 cm is enlarged by 3:1, what is the area after the enlargement?
将长为10厘米，宽为5厘米的长方形按3：1扩大，则扩大后的面积是多少平方厘米．
<gadget id="calculator">10 * 3</gadget>
<output>30</output>

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

<gadget id="calculator">30 * 15</gadget>
<output>450</output>

<result>450</result>