This is an absolute value function which creates a V for its graph. Since the absolute value is on y, the function is rotated to the right or sideways.
This means only the x values of 0 and greater are used in the function. Since the domain is the set of all x values then it is x≥0.
This also means that all y values are used on the y-axis. There is no restriction on the y values. Since the range is the set of all y values then it is all real numbers.
The first equation will turn into -18x -6y = -18, and the second equation will turn into 14x + 6y = 18. The y terms will cancel out when you add the equations together.
