9514 1404 393
Answer:
285
Step-by-step explanation:
Put the numbers where the variables are and do the arithmetic.
[tex]\dfrac{x^2y-2z}{4}=\dfrac{12^2\cdot8-2\cdot6}{4}=\dfrac{144\cdot8-2\cdot6}{4}\\\\=\dfrac{1152-12}{4}=\dfrac{1140}{4}=\boxed{285}[/tex]