Party A and Party B are assigned to complete the project within m days and n days respectively.

1/m + 1/n= 1/24

18x( 1/m+ 1/n)+( 10/m)= 1

Simultaneous solution

m=40，n=60

So it takes 40 days and 60 days for Party A and Party B to complete it alone.

1. The expenses independently completed by Party A: 40× 0.6 = 240,000 yuan.

2. The expenses independently completed by Party B: 60× 0.5 = 300,000 yuan.

3. Cost of cooperation between Party A and Party B: 24× (0.6+0.5) = 264,000 yuan.

4. Verify the cooperation between Party A and Party B for a few days, and then Party A or Party B will complete the remaining projects.

The cost is more than 240 thousand yuan.

Therefore, it takes 40 days to complete all the arrangements of A.