Summarize and mutate w if condition

Hi, how can I group my table by a certain column and then add the total count and then add another column using mutate function in which added column needs to have a count if a condition is met?

Below is my starting point but not working!!

df1 <- df %>% group_by(ticker,company) %>%
summarize(count = n()) #%>%
#ungroup() %>% mutate(count4 = sum(df$EPS == "4")


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