Calculate SSE using R output 
Hi I'm confused about how to manually calculate SSE using R output. I'm thinking about using residual standard error and maybe the relationship between SSE, SSR and SSTO, but not sure what's next. My R output is attached below. Any help is appreciated!!!

There is a relationship between the sun of the squared residuals (what you call SSE) and what R calls “residual standard error” (what I’ll call $RMSE$).
$$
RMSE =\sqrt{\dfrac{SSE}{n-p}}\\\iff\\SSE=
RMSE^2\times (n-p)
$$
That $n-p$ term is the sample size minus the number of estimated regression parameters, and it is called the “degrees of freedom”.
You have an $RMSE=9.528$ on $227$ degrees of freedom. Thus:
$$
SSE =9.528^2\times 227
$$
This does not quite match the answer you cite as the correct answer, but that is due to R rounding the printout. If you extract the residual standard error from the linear model output, your answer should match.
