A 40cm long iron wire exactly forms a rectangle whose length to width ratio is 5:3, find the area of this rectangle.
一根长40cm的铁丝正好围成一个长与宽的比是5：3的长方形，求这个长方形的面积．
<gadget id="calculator">40 / 2</gadget>
<output>20</output>

<gadget id="calculator">5 + 3</gadget>
<output>8</output>

<gadget id="calculator">5 / 8</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">20 * (5/8)</gadget>
<output>25/2 = around 12.5</output>

<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">20 * (3/8)</gadget>
<output>15/2 = around 7.5</output>

<gadget id="calculator">(25/2) * (15/2)</gadget>
<output>375/4 = around 93.75</output>

<result>375/4 = around 93.75</result>