The circumference of a circular flower bed is 31.4 meters, and 40% of the land in the flower bed is planted with rose flowers. How many square meters is the area for planting rose flowers?
一个圆形花坛周长是31.4米，花坛中40%的土地种植月季花，种月季花的面积是多平方米？
<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">25 * 3.14</gadget>
<output>78.5</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">78.5 * (2/5)</gadget>
<output>31.4</output>

<result>31.4</result>