The perimeter of a rectangle is 40m, and the ratio of length to width is 4:1. What is the area of the rectangle in m**2.
一个长方形的周长是40m，长与宽的比是4：1，这个长方形的面积是多少m**2．
<gadget id="calculator">40 / 2</gadget>
<output>20</output>

<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">20 * (4/5) * 20 * (1/5)</gadget>
<output>64</output>

<result>64</result>