If a rectangle with an area of 5 square centimeters is enlarged at a ratio of 1:3, what is its area after the enlargement?
一个面积是5平方厘米的长方形，按1：3的比例扩大，则扩大后它的面积为多少平方厘米．
<gadget id="calculator">5 * 9</gadget>
<output>45</output>

<gadget id="calculator">45 - 5</gadget>
<output>40</output>

<result>40</result>