Intermediate Algebra (6th Edition)

$z$ - $\frac{1}{2}$ $=$ $z$ $\times$ $\frac{1}{2}$
The "difference" means subtraction; using the values in the order they are given in the problem. The difference of $z$ and one-half. $z$ - $\frac{1}{2}$ "is" translates into an equals sign: $=$ The "product" means to multiply the values given. $z$ $\times$ $\frac{1}{2}$ OR $z$ - $\frac{1}{2}$ $=$ $z$ $\times$ $\frac{1}{2}$