To solve this simply divide 4 by 3 and use the long division and do the same for 11 and 9, then compare the values.
A decay rate of 26.3% per minute means that for every minute that passes, there remains 73.7% of the amount of the substance available at the end of the previous minute.
If 
is the starting amount, and 
is the amount left after 
minutes, then
and so on, such that
We have 
grams at the start, so after 7 minutes we're left with
Answer: 30 people
In the first vineyard, it needs 25 people working for 9 days to finish 30 acres of vineyard. Using this information you can determine the worker speed. The number of worker and days were given will increase the speed, but the area of the vineyard will decrease it. The calculation would be:
Worker speed= worker number * times given / vineyard area
Worker speed= 25 people * 9 days / 30 acres = 7.5 people days /acres
Applying the same calculation into the second vineyard would be:
Worker speed= worker number * times given / vineyard area
7.5 people days /acres = worker number * 5 days / 20 acres
Worker number= (7.5 people days /acres ) / 5 days x 20 acres= 30 people
