Error: Cannot use `+.gg()` with a single argument.

Hello,

I got this error:
Error: Cannot use `+.gg()` with a single argument. Did you
accidentally put + on a new line?

After running this:
data(murders)
library(ggplot2)
library(dplyr)
library(ggplot2)
ggplot(data=murders)

#define the slope of the line
r<-murders %>% summarize(rate=sum(total)/sum(population)*10^6) %>%.$rate
#mamke the plot
murders %>% ggplot(aes(population/10^6,total,label=abb))+
  +geom_abline(intercept = log10(r),lty=2,color="darkgrey")+
  +geom_point(aes(col=region), size=3)+
  +geom_text_repel()+
  +scale_x_log10()+
  +scale_y_log10()+
  +xlab("Populations in millions (log scale)")+
  +ylab("Total number of murders (log scale)")+
  +ggtitle("US Gun Murders in US 2010")+
  +scale_color_discrete(name="Region")+
  +theme_economist()

Is this an issue with my dplyr? Or how I can fix this code in order to
work?

Thanks
Ana