5/18 + 7/12 =

\[\frac{5}{18} + \frac{7}{12} = \frac{5 \times 2}{18 \times 2} + \frac{7 \times 3}{12 \times 3} = \frac{10}{36} + \frac{21}{36} = \frac{10+21}{36} = \frac{31}{36}\]