diff --git a/transform.Rmd b/transform.Rmd
index 30fac27..822f0b4 100644
--- a/transform.Rmd
+++ b/transform.Rmd
@@ -277,7 +277,7 @@ There are a number of helper functions you can use within `select()`:
    
 See `?select` for more details.
 
-`select()` can be used to rename variables, but it's rarely useful because it drops all the variables not explicitly mentioned. Instead, use `rename()`, which is a variant of `select()` that keeps all the variables that aren't explicitly mentioned:
+`select()` can be used to rename variables, but it's rarely useful because it drops all of the variables not explicitly mentioned. Instead, use `rename()`, which is a variant of `select()` that keeps all the variables that aren't explicitly mentioned:
 
 ```{r}
 rename(flights, tail_num = tailnum)