If a rectangle with a length of 5 cm and a width of 3 cm is enlarged by 3:1, what is the area of the figure obtained?
把一个长5厘米，宽3厘米的长方形按照3：1放大，得到的图形的面积是多少．
<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">15 * 9</gadget>
<output>135</output>

<result>135</result>