Answer
$$ -\frac{7}{30} $$
Work Step by Step
We know that two negatives is the same as a positive. Thus, the problem simplifies as follows:
$$ = -\frac{8}{15} -(-\frac{3}{10} ) \\ = -\frac{8}{15} +\frac{3}{10} \\ -\frac{16}{30} + \frac{9}{30} \\ = -\frac{7}{30} $$
