There are several ways to generate an equation of a line. You are given two points, so from these two points you can find the slope of the line, then using one of these points and the slope you calculated, plug them into the point-slope formula and you will have your equation.

The choice of which is x and which is y is up to you, but normally you see "time" as the x-axis. If you use this convention, then "life-expectancy in years" would be your y-axis.

From these choices, P1=(2000, 76.1) and P2 = (2007, 78.2). From these two points you can calculate the slope m. Do you know how to do that?

Then when you have the slope, you use either of the above points and create the point-slope form of a linear equation,