Chapter 1 - Section 1.2 - Operations with Real Numbers and Simplifying Algebraic Expressions - Exercise Set - Page 27: 21

$-\dfrac{35}{36}$

Make the fractions similar using their LCD, which is $36$, to obtain: $=-\dfrac{8}{36} - \dfrac{27}{36}$ RECALL: $a-b = a+(-b)$. Thus, $-\frac{8}{36} - \frac{27}{36}=-\frac{8}{36} +\left(-\frac{27}{36}\right)=-\frac{35}{36}$