Solve for $d$
$$2x-2yd=y+xd$$ $$2(x-yd)=y+xd$$ $$2(x-yd)-y=xd$$ $$\frac{2(x-yd)-y}{x}=d$$ Now I think this is wrong considering I have a $d$ on the other side and I would have to reverse my work and end up at the beginning. Any small pointers or tips? Thanks!