Answer
$\frac{18n+11}{12}$
Work Step by Step
By inspection, we see that the LCM of the denominators is $12$. Therefore, we create a common denominator using this LCM and obtain:
$\frac{3n-1}{3}+\frac{2n+5}{4}$
=$\frac{4(3n-1)+3(2n+5)}{12}$
=$\frac{12n-4+6n+15}{12}$
=$\frac{12n+6n-4+15}{12}$
=$\frac{18n+11}{12}$
