Answer
$\dfrac{3x+5}{12}$
Work Step by Step
When adding two fractions with common denominators, we add the numerators and copy the denominator. Therefore, the given expression, $
\dfrac{x}{12}+\dfrac{2x+5}{12}
,$ simplifies to
\begin{array}{l}\require{cancel}
\dfrac{x+2x+5}{12}
\\\\=
\dfrac{3x+5}{12}
.\end{array}