3 people eat 3 watermelons and eat them in 3 minutes. How many minutes does it take for 15 people to eat 15 watermelons?
3个人吃3个西瓜，用3分钟吃完．15个人吃15个西瓜要多少分钟．
<gadget id="calculator">15 / 15</gadget>
<output>1</output>

<gadget id="calculator">3 / 3</gadget>
<output>1</output>

<gadget id="calculator">1 * 1 * 3</gadget>
<output>3</output>

<result>3</result>