Sum of $$8 / 3$$ and $$4 / 7$$ is calculated as below
$$8 / 3 + 4 / 7 = (56 + 12) / 21$$
We get,
$$= 68 / 21$$
Product of $$- 3 / 7$$ and $$14 / 9$$ is calculated as follows:
$$- 3 / 7 \times 14 / 9 = - 2 / 3$$
Hence,
$$68 / 21 \div - 2 / 3 = 68 / 21 \times 3 / - 2$$
We get,
$$= 34 / - 7$$
$$= \left \{34 \times (- 1)\right \} / \left \{- 7 \times (- 1)\right \}$$
$$= - 34 / 7$$
$$= -4\dfrac {6}{7}$$.