Which predictors are considered significant if we work with α=0.05? Which predictors can be eliminated? What is the final model if we only use FloorArea and Offices as predictors?

Regression Modeling

Construct a multiple regression model.

Use Excel’s Analysis Tool Pak to conduct a regression analysis with Assessment Value as the dependent variable and Floor Area, Offices, Entrances, and Age as independent variables. What is the overall fit r^2? What is the adjusted r^2?
Which predictors are considered significant if we work with α=0.05? Which predictors can be eliminated?
What is the final model if we only use Floor Area and Offices as predictors?
Suppose our final model is:
Assessed Value = 115.9 + 0.26 x Floor Area + 78.34 x Offices
What would be the assessed value of a medical office building with a floor area of 3500 sq. ft., 2 offices, that was built 15 years ago? Is this assessed value consistent with what appears in the database?