According to the meaning of the question, the number of people going to site A in the morning is 3/(3+ 1)=3/4, and the number of people going to site B is 1-3/4 = 1/4.

In the afternoon, the number of people going to site B is 5/ 12, and the number of people going to site A is1-5/12 = 7/12.

Suppose the daily workload of these workers is "1",

Then: the workload of station A is 3/4×1/2+7/12×1/2,

The workload of site B is (3/4×1/2+7/12×1/2) ÷ 3/2.

Site B has been completed1/4×1/2+5/12×1/2,

The remaining workload is (3/4×1/2+7/12×1/2) ÷ 3/2-(1/4×1/2+5//kloc.

Then there are 4÷ 1/9=36 workers.