Divide two ropes of 45 cm and 30 cm into the same small pieces, and there is no residue, what is the longest length of each piece?
将45厘米和30厘米的两根绳子分成同样的小段，且没有剩余，每段最长是多少厘米？
<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<result>15</result>