The diameter of the large circle is three times the diameter of the small circle. If the diameter of the large circle is 15 centimeters, what is the diameter of the small circle in centimeters?
大圆的直径是小圆直径的3倍，已知大圆的直径是15厘米，则小圆的直径是多少厘米．
<gadget id="calculator">15 / 3</gadget>
<output>5</output>

<result>5</result>