Use the Teams data in Lahman package. The team IDs corresponding to Brooklyn baseball teams are listed as: $$BR$1,$BR$2,$BR$3,$BR$4,$BR$,$BRP$,$BRF$$

Keep the variables teamID, HR $($home runs$)$ and HRA $($homeruns allowed$)$ in R markdown

Keep only Brooklyn baseball teams $($BR$1,$BR$2,$BR$3,$BR$4,$BR$,$BRP$,$BRF$)$ in R markdown

Choose one apply function to find the average home runs $($HR$)$ and average homeruns allowed $($HRA$).$ How can I write the code in R markdown to keep only the Brooklyn baseball teams. I tried but I keep getting an error.