The value of y varies jointly with the values of x and z. When $\displaystyle{x}={4}\usepackage{cmbright}\Huge\$ and $\displaystyle{z}={10}\usepackage{cmbright}\Huge\$ , the value of y is 360.

What is the value of y when $\displaystyle{x}={5}\usepackage{cmbright}\Huge\$ and $\displaystyle{z}={12}\usepackage{cmbright}\Huge\$ ?