The two projects A and B are completed by two engineering teams A and B respectively. On a sunny day, engineering team A completed it in 12 days, and engineering team B completed it in 15 days. In rainy days, the work efficiency of engineering team A decreases (1/2), and that of engineering team B decreases (1/4). As a result, the two engineering teams A and B started and completed the work at the same time. During this period, how many days are there rainy days?
甲乙两项工程分别由A、B两工程队完成．在晴天，A工程队12天完成，B工程队15天完成．在雨天，A工程队工效下降(1/2)，B工程队工效下降(1/4)．结果A、B两工程队同时开工且同时完工．在这期间，雨天有多少天？
<result>12</result>