If a rectangle has a perimeter of 80 meters and a ratio of length to width of 5:3, what is the area in square meters?
一个长方形地，周长是80米，长与宽的比是5：3，则面积是多少平方米．
<gadget id="calculator">5 + 3</gadget>
<output>8</output>

<gadget id="calculator">80 / 2 / 8</gadget>
<output>5</output>

<gadget id="calculator">5 * 5 * 3 * 5</gadget>
<output>375</output>

<result>375</result>