Answer :
First what you want to do is isolate the n, so to do that, get rid of 3n on the right by subtracting it from both sides. You now have 4n+3=27. Now get rid of 3 by subtracting it from both sides. Now the equation is 4n=24. Divide both sides by 4 and you get n=6.
[tex]7n+3=3n+27 \\\\ 7n-3n=27-3 \\\\ 4n=24 \\\\ \boxed{n=\frac{24}{4}=6}[/tex]