I have to finish this Rstudio code for a class

library(tidyverse) library(nycflights13) flights

#### 3. For each of the three major US airlines, how many flights have operated only once in the whole year? ```{r} flights %>% filter( ) %>% group_by(carrier, flight) %>% summarise(count=) %>% filter() %>% group_by(carrier) %>% summarise(count1=n())