There are two variables but only one equation, so it can't be solved uniquely because there are many solutions. However, we can express y in terms of x and we can show the relationship between x and y.
So y/2=1-x/4; multiply through by 4: 2y=4-x or x=4-2y or y=½(4-x) or x+2y=4. The relationship can be shown graphically as a straight line.Draw a line though the y intercept (y=2) and x intercept (x=4).