One ribbon is 30 cm long and the other ribbon is 45 cm long. Cut these two ribbons into short ribbons of the same length and there is no surplus. What is the longest length of each short ribbon?
一根彩带长30厘米，另一根彩带长45厘米，把这两根彩带剪成长度一样的短彩带且没有剩余，每根短彩带最长是多少厘米？
<gadget id="calculator">3 * 5</gadget>
<output>15</output>

<result>15</result>