Hi Shelley. What your attached image shows is not a system of equations, as far as I can tell. The text which precedes these four equations says "Each equation represents one of the hanger diagrams." I'm not familiar with hanger diagrams, but it seems from the text that these are four separate equations. 2y = x is a simplification of the other three equations in your example,
If the student is asked to express one variable in terms of another, that would be solving a system of equations. For example, that second equation "2y = x" is expressing x in terms of y. That might be a solution to a system. But in this case, it is just simplifying the terms of each of the other three equations.
If there is a mathematician reading this, please correct me if I am misinterpreting this topic. Maybe you can explain it better? Is "system of equations" an outmoded term?