To transform a rectangular flower bed with a length of 18 meters and a width of 5 meters, and the area remains the same, if the width is increased by 4 meters, how much should the length be reduced?
要改造一个长18米，宽5米的长方形花坛，面积不变，如果将宽增加4米，那么长应减少多少米？
<gadget id="calculator">5 + 4</gadget>
<output>9</output>

<gadget id="calculator">5 / 9</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">18 * (5/9)</gadget>
<output>10</output>

<gadget id="calculator">18 - 10</gadget>
<output>8</output>

<result>8</result>