Task $1$:

What are the unique values in the year$\_$built variable? How many occurrences are there for each unique value?

Task $2$:

Filter the dataframe fuel $\_$consumption so that variables electricity$\_$expense and water$\_$expense only contain values greater than $0.$ Overwrite fuel$\_$consumption.

Task $3$:

$$Create a new variable describing the total energy expenses $($energy$\_$expense $+$ electricity $\_$expense $+$ nat$\_$gas$\_$expense $+$ other$\_$fuel $\_$expense$)$ for each household. Name this variable total$\_$energy$\_$expense.

$$Sort the dataframe based on the variable you created in A

$$Identify the respondent with the highest and lowest total energy expenses.