To find z we must find the constant of proportionality A with the data they give us:
[tex]\begin{gathered} w=\frac{A}{z} \\ \end{gathered}[/tex][tex]\begin{gathered} w=5 \\ z=6 \\ A=w\cdot z \\ A=5\cdot6 \\ A=30 \end{gathered}[/tex]Now with the calculation of the constant we can find z when w = 10.
[tex]\begin{gathered} z=\frac{A}{w} \\ z=\frac{30}{10} \\ z=3 \end{gathered}[/tex]