Fill in the blanks using the commutative and additive identity properties. a) (-27) + (-52) = (-52) + b) (-27) + = (-27)

The commutative property of addition states that for any two integers $a$ and $b$, $a + b = b + a$.
Given the equation:

$$(-27) + (-52) = (-52) + \underline{\hspace{1cm}}$$

Comparing this to $a + b = b + a$, where $a = -27$ and $b = -52$, the blank must be $a$.

$$(-27) + (-52) = (-52) + (-27)$$

So, the blank is $\boxed{-27}$.

The additive identity property states that for any integer $a$, $a + 0 = a$.
Given the equation:

$$(-27) + \underline{\hspace{1cm}} = (-27)$$

Comparing this to $a + 0 = a$, where $a = -27$, the blank must be 0.

$$(-27) + 0 = (-27)$$

So, the blank is $\boxed{0}$.