You may want to review solving linear equations for one variable in terms of another first.
Most lines (actually, any line that isn't vertical) can be written as y = mx + b, where m and b are numbers. The number m is called the slope and the number b is called the y-intercept. If you're given the equation of a line, and need to find the slope and the y-intercept, just solve the equation for y. Then the number in front of the x is the slope and the number being added or subtracted is the y-intercept. (Of course, if it's subtracted instead of added, then that means the y-intercept is negative.)
Here are some things to keep in mind.