z⁷ · 8z⁴ =   z⁷ · 8 · z⁴

=  8 · z⁷ · z⁴              (Commutative property of multiplication: a × b = b × a)

Since base is common, apply the product of powers property: a^m · aⁿ = a^{m + n}.

=  8 · z^{7 + 4}  

=  8 · z¹¹                   (Add exponents: 7 + 4 = 11)

=  8z¹¹

Product of  z⁷ · 8z⁴ is8z¹¹.