As we all know associative property states, $$(a + b) + c = a + (b + c)$$
We can simply solve by using the property
$$\therefore \dfrac {19}{-5} + \left (\dfrac {-3}{11} + \dfrac {-7}{8}\right ) = \left \{\dfrac {19}{-5} + \left (\dfrac {-3}{11}\right )\right \} + \dfrac {-7}{8}$$.