Find the sum:

$\dfrac{8}{15} + \dfrac{5}{12}$

The denominators are different, so express the rational numbers with the LCM of their denominators as the common denominator and then add.

LCM of 15 and 12 = 60

$\dfrac{8}{15} + \dfrac{5}{12} = \dfrac{8 \times 4 + 5 \times 5}{60} \\[1em] = \dfrac{32 + 25}{60} \\[1em] = \dfrac{57}{60} \\[1em] = \dfrac{19}{20}$

Hence, $\mathbf{\dfrac{8}{15} + \dfrac{5}{12} = \dfrac{19}{20}}$.