The ratio of the lengths of the sides of a triangle is 3:4:5. Given that the perimeter of the triangle is 48 cm, what is the length of the longest side in cm?
一个三角形的三边长之比为3：4：5，已知这个三角形周长48厘米，求最长的边长是多少厘米？
<gadget id="calculator">3 + 4 + 5</gadget>
<output>12</output>

<gadget id="calculator">5 / 12</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">48 * (5/12)</gadget>
<output>20</output>

<result>20</result>