Please help solve clearly.

Using the College data set in R

(a) Using \"Expend\" as the response and the other variables as predictors, perform backward stepwise selection (Choose BIC as your criteria) on the training set in order to identify a satisfactory model that uses just a subset of the predictors. (b) Fit a (SAM on the training data, using \"Expend\" as the response and the features selected in the previous step {Part a) as your predictors. Plot the results. and explain your ndings. (c) Evaluate the model obtained on the testing data set. and explain the results obtained. (d) For which variables, if any, is there evidence of a non-linear relationship with the response