The municipal government wants to renovate a 60-meter-long street. Engineering team A can complete it in 10 days, and engineering team B can complete it in 15 days. If the two teams work together to transform at the same time, how many days can it be completed?
市政要改造一条60米长的街道，甲工程队10天能完成，乙工程队15天能完成．若两队同时合作改造，几天能完成？
<gadget id="calculator">60 / 10</gadget>
<output>6</output>

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

<gadget id="calculator">6 + 4</gadget>
<output>10</output>

<result>6</result>