The table lists average annual cost (in dollars) of tuition and fees at
private four-year colleges for selected years.
a) Determine a linear function f(x) = ax + b that models the data, where
== 0 represents 2013, x= 1 represents 2014, and so on. Use the
points (0, 24543) and (4, 29475) to graph f and a scatter diagram of the
data on the same coordinate axes. What does the slope of the
graph indicate?
b) Use the function from part (a) to approximate average tuition
and fees, to the nearest dollar, in 2016. Compare the approximation to
he actual figure given in the table, $27,956.
c) Use the linear regression feature of a graphing calculator to find the
equation of the line of best fit.

Part c is what I’m confused on how to do it.