To solve this expression, we need to follow the order of operations, which is PEMDAS (Parentheses, Exponents, Multiplication and Division from left to right, Addition and Subtraction from left to right).

First, we can simplify the expression within the parentheses:
23 x (-18) = -414
14 x (-8) = -112

Now we can substitute these values back into the original expression:
(-414 - (-112)) x (-15)
(-414 + 112) x (-15)
(-302) x (-15)

Now we can multiply -302 and -15 to get the final answer:
-302 x -15 = 4530

Therefore, the final answer is 4530.