A task is completed by A and B in cooperation, and the specified time is just used up when it is completed. If A’s work efficiency is increased by (1/5), then it only takes (9/10) of the specified time to complete the task; if B's work efficiency is reduced (1/4), then the two need to delay 2.5 hours to complete the task. How many hours is the specified time?
某任务由甲、乙两人合作完成，完成时刚好用完规定的时间，若甲的工作效率提高(1/5)，那么只需用规定时间的(9/10)就能完成任务；若乙的工作效率降低(1/4)，那么两人需延迟2.5小时才能完成任务．规定时间是多少小时？
<result>20</result>