To dig a canal, engineering team A digs the entire canal (1/20) every day, and engineering team B digs the entire canal (1/30) every day. The two teams work together. How many days to finish digging?
挖一条水渠，甲工程队每天挖整条水渠的(1/20)，乙工程队每天挖整条水渠的(1/30)，两队合作，几天挖完？
<result>5</result>