Answer:
Step-by-step explanation:
If the population increases at a rate of 4% per annum, then:
In year 1:
Where 
is the initial population and 
is the population in year n
In year 2
It can also be written as:
Taking out common factor
Taking out common factor (1 + 0.04)
Taking out again common factor
Simplifying
So
This is the equation that represents the population for year n
Then, in 4 years, the population will be:
You find 8% of 55.35 which is 4.42
Then you find 15% of 55.35 which is 8.30
You add them together which equals 12.72
You then subtract 12.75 from 55.35 55.35-12.75=42.63
The original price was $42.63
Add the equations,just the way they appear there.
-- Add the top 'x' to the bottom 'x'. Write the sum under the 'x's.
-- Add the '+y' and the '-y'. Write the sum under the 'y's.
-- Add the '2' and the '4'. Write the sum under them, with n " = " sign
before it.
You should now have an equation with only 'x' in it and no 'y'.
You can easily solve that one and find out the value of 'x'.
Once you know the value of 'x', go back to either one of the original
equations, and plug the number-value of 'x' in place of 'x'.
You'll then have an equation with only 'y' in it and no 'x'.
You can easily solve that one and find out the value of 'y'.
400+80+13 = 493 is the number.
