Answer:
10 days
Step-by-step explanation:
Mr Datu can pay 8 workers for 15 days,
Then at the same rate he can pay 1 worker for the number of days = 15×8
= 120
If he adds number of workers = 4
Then total number of workers = 8 + 4 = 12
With the same rate Mr Datu can pay 12 workers for number of days = 
= 10 days
Therefore, Mr Datu can pay 12 workers for 10 days a the same rate.
In order from least to greatest, it's listed as:
0.015, 0.105, 0.15, 0.501.
0.015 is the lowest number because it is the farthest from being a whole. It starts with .0, whereas the rest of them have a number higher than 0 after the period.
Let blank =x
4+x=3+4
4+x=7
-4 -4
x= 7-4
x=3
blank is 3