The total workload is set to 1, the efficiency of Xiaohua is 1/3, the efficiency of Xiaofang is 1/4, and that of Xiaomei is 1/5. You add up the efficiency of three people, and then divide the total efficiency of three people by the total workload "1" to get the required number of days. The formula is as follows:
It is approximately equal to (1.3 days) completion.