The line of best fit can be found on the TI 84 calculator.
There is a step-by-step example of how to calculate the line of best fit for the following dataset.
The data values will be entered first.Then press EDIT.The x-values of the dataset are in column L1.
Then press VARS and scroll over to Y-VARS, then press ENTER.
How to create a residual plot on a TI-84 calculator.