The perimeter of a triangle is 81 cm, the ratio of the three sides is 2:3:4, what is the shortest side in cm?
一个三角形的周长是81厘米，三条边的比是2：3：4，其中最短的一条边是多少厘米．
<gadget id="calculator">2 + 3 + 4</gadget>
<output>9</output>

<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">81 * (2/9)</gadget>
<output>18</output>

<result>18</result>