If one square is divided into 9 smaller equal squares, then they have to be arranged in 3 lines of 3, that is 3 smaller equal squares per side of the original big square. That said, the area of the big square is equal to the multiplication of 3 small squares sides times 3 small squares sides, call x the length of the small squares.
So,
area = 9 = 3x*3x
9x^2 = 9
x^2 = 1
x = 1
therefore the smaller squares have sides of 1 unit
The answer is 31,500.
Let's clarify some things :
1% of 45,000 is 450
Maybe you're wondering why , it's actually very simple .
Just move the decimal to the left once if you want to find 10% , move the decimal twice if you want to find 1%.
We now that 1% equals 450. Then 2% equals to....
Well just add another 1% .
450 + 450 or 450 times 2
Which equals 900.
Now we want to find what's the population after 15 years.
900 times 15= 13,500
But that's not the answer ....
That's what is decreasing.
45,000 - 13,500= 31,500
That's why the answer is 31,500.
About 49 pounds
$5.75 x 2 = 11.50
561.60 / 11.50 = 48.83 (round)
49 lbs
I'll use my own formula (similar to yours tho)

A=future amount
p=invested
r=rate in decimal
n=number of times per year compounded
t=time in years
so
when will A=2P
subsitute 2P for A
also quarterly means 4 times a year or n=4
and 12%=0.12=r
so

divide both sides by P

simplify


take the ln of both sides



divide both sides by 4ln(1.03)

use calculator
5.86244=t
about 5.9 years
3) an $8 delivery fee and $1.50 per litre of water
This is because the $8 is a constant baseline, then adding $1.50 times the amount of litres purchased.