x_2019<- read_xlsx("class_enrollment_summary_by_term_2.26.19.xlsx", skip = 3) %>% 
  clean_names() %>% 
  filter(!is.na(course_name)) %>% 
  select(course_title, course_name, u_grad)

x_2018<- read_xlsx("class_enrollment_summary_by_term_03.06.18.xlsx", skip = 3) %>% 
  clean_names() %>% 
  filter(!is.na(course_name)) %>% 
  select(course_title, course_name, u_grad)

all<- inner_join(x_2019, x_2018, by = "course_title", suffix = c(".2019", ".2018"))

Including Plots

You can also embed plots, for example:

Note that the echo = FALSE parameter was added to the code chunk to prevent printing of the R code that generated the plot.