A reply to this question and How set labels on the X and Y axises by equal intervals in R ggplot?
mtcars %>% ggplot(aes(mpg, disp)) + geom_point() + geom_smooth() + scale_y_continuous(limits = c(0, 500), breaks = seq(0,500,50)) + scale_x_continuous(limits = c(0,40), breaks = seq(0,40,5))