To add fractions, they must have the same denominator. If they have then we add their numerators. Hence,
\(\displaystyle\frac{{1}}{{6}}+\frac{{1}}{{6}}=\frac{{{1}+{1}}}{{6}}\)

\(\displaystyle\frac{{1}}{{6}}+\frac{{1}}{{6}}=\frac{{2}}{{6}}\)

Reduce to lowest terms: \(\displaystyle\frac{{1}}{{6}}+\frac{{1}}{{6}}=\frac{{1}}{{3}}\)

\(\displaystyle\frac{{1}}{{6}}+\frac{{1}}{{6}}=\frac{{2}}{{6}}\)

Reduce to lowest terms: \(\displaystyle\frac{{1}}{{6}}+\frac{{1}}{{6}}=\frac{{1}}{{3}}\)