Your formula for this is

and

. Get everything on one side of the equals sign, set it equal to 0 and factor. When you do this you get (x-3)(x+27). The Zero Product Property rule tells us that either x-3 = 0 or x+27 = 0 and that x = 3 and -27. The only thing in math that will NEVER be negative besides time is distance/length, therefore, x cannot be 27 and has to be 3.
Write the first few terms of the sequence.
f₁ = 6
f₂ = f₁ + 5 = 11
f₃ = f₂ + 5 = 16
f₄ = f₃ + 5 = 21
and so on
The sequence is
6, 11, 16, 21, ...,
This is an arithmetic sequence with a common difference of 5.
In function notation, the sequence is

This represents the equation of a straight line with n as the independent variable and f as the dependent variable.
The slope is 5.
A graph of the line is shown below.
Answer:
The sequence is

The slope is 5.
Just multiply man 2*4 2*3 1.5*4 and 1.5*3.
In 7 years, the car was 18,000 and after 5 years it is worth 10,500 so if you subtract 18000-10500=7500 and if you do 7500/5=1500 so this means that the car was going down 1500 in value every year.