Use 40 decimeters of iron wire to form a rectangle so that the length is 4 times the width. What is the area of the rectangle?
用40分米长的铁丝围成一个长方形，使长是宽的4倍，围成的长方形的面积是多少平方分米？
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">40 / 2 / 5</gadget>
<output>4</output>

<gadget id="calculator">4 * 4 * 4</gadget>
<output>64</output>

<result>64</result>