3 A particle is in equilibrium when acted on by the forces \(\left( \begin{array} { r } x
- 7
z \end{array} \right) , \left( \begin{array} { r } 4
y
- 5 \end{array} \right)\) and \(\left( \begin{array} { r } 5
4
- 7 \end{array} \right)\), where the units are newtons.

1. Find the values of \(x , y\) and \(z\).
2. Calculate the magnitude of \(\left( \begin{array} { r } 5
   4
   - 7 \end{array} \right)\).