Question 110632
You haven't provided enough information to answer your questions specifically, because you haven't provided the y, or salary values for each of the x or year coordinates.
:
So, what I'm going to do is make up a set of numbers that describe a linear relationship and answer your questions based on those made-up numbers.  Unless we are very, very fortunate, you will have to go back and do the problem over again using the numbers that you are given.
:
I'm going to assume that Bob made $60,000 in 2002, and increased by $5,000 per year for the following three years, so:
:
2002 - 60000 
2003 - 65000
2004 - 70000
2005 - 75000
:
Since 2002 is {{{t[0]}}}, represent 2002 by x = 0, 2003 by x = 1, etc.
:
The coordinates are therefore:
(0,60000)
(1,65000)
(2,70000)
(3,75000)
:
The slope of a line is given by {{{m=(y[2]-y[1])/(x[2]-x[1])}}}, so
:
{{{m=(65000-60000)/(1-0)=5000}}}
:
The y-intercept is the value of y when x is 0, which is just our first point, so the intercept is 60000.  Now we know enough to write the equation in slope intercept form.
:
{{{y=5000x+60000}}}
:
Since 2005 is represented by x = 3, 2008 must be represented by x = 6, so his salary in 2008 at the current rate of increase would be given by:
:
{{{y=5000*6+60000=90000}}}
:
Remember to go back and plug in the real numbers from this problem, then re-do the arithmetic.