The linear equation

y=0.15x + 0.79


represents an estimate of the average cost of gas for year x starting in 1997. The year 1997 would be represented by x = 1, for example, as it is the first year in the study. Similarly, 2005 would be year 9, or x = 9.

a)What year would be represented by x = 4?

b)What x-value represents the year 2018?

c)What is the slope (or rate of change) of this equation?

d)What is the y-intercept?

e)What does the y-intercept represent?

f)Assuming this growth trend continues, what will the price of gasoline be in the year 2018? How did you arrive at your answer?

2 answers

would a be 2001?
If they're sratring at

x = 1 -> Y1 = 1997 , then
x = 2 -> Y2 = 1998

then you can just count for a) and b)

In the formula y = mx + c, m is the slope and c is the y-intercept, which should answer a couple of them.

f) Once you've counted to 2018, just let x equal that year number; that'll let you work out y.