Show price, air_cond, heat, fireplaces for houses that have no fireplaces

Create a new variable price_per_bedroom which is price divided by the number of bedrooms. Show only price, bedrooms, and price_per_bedroom columns and arrange the rows in the descending order of price_per_bedroom

Create a new variable has_4_or_more_bedrooms which is TRUE if the house has 4 or more bedrooms and FALSE otherwise. Use this variable and group_by and summarise() to find how many houses have 4 or more bedrooms and how many dont