How many observations are from females in a household with a woodburning stove and a parent who smokes and who have a prebronchodilator peak flow of no more than 350?

08 {r } # How many observations are from females in a household with a woodburning stove and a parent who smokes and who have a prebronchodilator peak flow of no more than 350? nrow(CAMP [CAMP$GENDER == "female" & CAMP$woodstove == "Yes" & CAMP$parent_smokes == "Yes" & CAMP$PREPF