As it stands, (dy/dy)-(2y/x)=3x is the same as: 1-(2y/x)=3x, x-2y=3x², y=½(x-3x²).
However, it’s more likely that (dy/dy) should have been (dy/dx) or (dx/dy).
Let’s assume :
(dy/dx)-(2y/x)=3x.
Multiply through by 1/x²: (1/x²)(dy/dx)-(2y/x³)=3/x.
(d/dx)(y/x²)=3∫dx/x=3ln(ax) where a is a constant.
Therefore y/x²=3ln(ax), y=3x²ln(ax).