The dataset store$\_$sales.csv comprises a subset of data collected from a U$.$S$.-$based retailer between $2010$ and $2012.$ It details weekly sales figures, with each row representing a distinct week of data for a specific store and department.

Notes: The dataset includes periods from $2010$ to $2012,$ but it does not cover every week. Do NOT extrapolate to fill in the missing weeks unless specifically instructed, as it will alter the results. Assume we are using the full dataset for most of the questions.

store: store location id

dept: store department id

date: first day of given week

weekly$\_$sales: sales for that week, dept, store

isholiday: binary variable, true indicates a holiday week. What is the average value of weekly$\_$sales for dept $1$ when there is no holiday?

Round your answer to the nearest dollar $($e$.$g$.,$ $$64\mathrm{.}5$ rounds up to $$65,$ while $$64\mathrm{.}49$ rounds down to $$64).$ Provide codes in R