60 students go rowing and sit in 3 big boats and 6 small boats respectively. It is known that the number of people sitting in each big boat is three times that of the small boats. How many students are there on each big boat.
60名同学去划船，分别坐在3条大船和6条小船上，已知每条大船上坐的人数是小船坐的人数的3倍．每条大船上有多少名同学．
<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">9 + 6</gadget>
<output>15</output>

<gadget id="calculator">60 / 15</gadget>
<output>4</output>

<gadget id="calculator">3 * 4</gadget>
<output>12</output>

<result>12</result>