par(mfrow=c(1, 2), mar=c(1, 1, 2, 1), pty="s")
par(cex=0.7)
plot(datasets::cars, ann=FALSE, axes=FALSE, col="gray", pch=16)

lmfit <- lm(dist ~ speed, datasets::cars)
abline(lmfit)
arrows(15, 90, 19, predict(lmfit, data.frame(speed=19)),
       length=0.1)
text(15, 90, "Line of best fit", pos=2)

box(col="gray")

mtext("abline() & arrows()", side=3, line=0.5)
plot(datasets::cars, ann=FALSE, axes=FALSE, col="gray", pch=16)

rug(datasets::cars$dist, side=2)

box(col="gray")

mtext("rug()", side=3, line=0.5)