Consider the calculation $\displaystyle{x}-{y}+{\left(-{z}\right)}\usepackage{cmbright}\Huge\$ where $\displaystyle{x}\usepackage{cmbright}\Huge\$ and $\displaystyle{z}\usepackage{cmbright}\Huge\$ are positive real numbers and $\displaystyle{y}\usepackage{cmbright}\Huge\$ is a negative real number.

i) What are the directions of motion for this calculation?

ii) Is the final answer positive, negative, or undetermined?