There are three groups of workers A, B, and C. Group A needs 5 people to complete the work of 3 people in Group A; 5 people in Group C need to complete the work of 4 people in Group B. A project, 12 people in group A and 16 people in group B cooperated to complete it in 3 days. If 15 people in Group C are asked to do it, how many days will it take to complete it?
有甲、乙、丙三组工人，甲组3人的工作，乙组需5人完成；乙组4人的工作，丙组需5人完成．一项工程，甲组12人，乙组16人合作3天完成．如果让丙组15人去做，那么需多少天完成．
<gadget id="calculator">300 + 240</gadget>
<output>540</output>

<gadget id="calculator">3 / 180</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">540 * (1/60)</gadget>
<output>9</output>

<result>9</result>