A piece of iron wire can form a square with a side length of 5 cm. If this wire is used to form a rectangle with a length of 7 cm, what is the width of the rectangle?
一根铁丝可以围成边长是5厘米的正方形，如果用这根铁丝围成长是7厘米的长方形，那么这个长方形的宽是多少．
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<gadget id="calculator">10 - 7</gadget>
<output>3</output>

<result>3</result>