Let $x$, $y$ and $z$ be distinct prime numbers,
$$\begin{aligned}
& x ( z - y ) = 18 \\
& y ( z - x ) = 40
\end{aligned}$$
the equalities are given.
Accordingly, what is the sum $\mathbf { x } + \mathbf { y } + \mathbf { z }$?
A) 17
B) 19
C) 21
D) 23
E) 25