The area is 10 just use a area calculator!
10)

11)

12)

13) (your answer is incorrect)

14) (your answer is incorrect)

15)

16)
-expression to represent this situation

Answer: In 1 group 57 students
/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
P.S. Hello from Russia :^)
9.This is because it goes through the whole circle passing through the centre point. at the full width
The rest are pretty easy. I'm sure you can manage. Good luck!
So, let's first focus on the first year:
the population then would be: 23000* (100+2)%
100% is the old population the 2% is the incease, so in total it's 102%, or 1.02 - the same number written differently.
So it will be 23000*1.02
After two years it will be 23000*1.02*1.02, and so on
so after x years it will be:
y=23000*