Your graphing calculator is a great tool! Get comfortable with it and it will save you lots of time and effort.
To perform a linear regression:
1) Press Stat, then Edit.
2) Enter your inputs (x-values) in L1 and your outputs (y-values) in L2
3) Press Stat, arrow over to Edit, and then select 4: Lin Reg
4) Arrow down to Calculate button, and press enter.
5) The calculator gives you the slope as "a" and the intercept as "b". Rounding to the nearest hundredth is a good idea, if the question doesn't specify!
Use the equation you are given to make predictions!