geom Extra Lines| Adding a line in ggplot

geom_vline()
geom_hline()
geom_abline()

library(ggplot2)
library(patchwork)

P1 <- ggplot(mtcars)+ geom_point(aes(mpg, cyl)) +
  geom_vline( xintercept = 20) + ggtitle('vline') +theme_light()
P2 <- ggplot(mtcars)+ geom_point(aes(mpg, cyl)) +
geom_hline( yintercept = 7) + ggtitle('hline') +theme_light()
P3 <- ggplot(mtcars, aes(wt, mpg)) + geom_point() + geom_abline(intercept = 25, slope = -1) +
  ggtitle("abline")+theme_light()

P3|(P1/P2)

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