Create a quadratic mileage term. Create two models to predict TPrice, one with only Mileage and another

Question:

Create a quadratic mileage term. Create two models to predict TPrice, one with only Mileage and another with both Mileage and (Mileage)2 (called MileSq).
a. How much does the R2 value increase if a quadratic term is added to the model TPrice = β0 + β1( Mileage)?
b. Look at plots of residuals versus Mileage in both models. Did the addition of the MileSq term improve the residual plots?