text: If p and q are both non-zero, the answer is y=0 (by inspection).  If q=0, then y can be any real number, since the equation becomes y/p=y/p.\n\nFor a more general answer, cross multiplying gives you y(p+q)=y(p-q).  If y is non-zero, you can divide it out, giving\n\np+q=p-q\n\nThis is only true if -q=q, which only happens when q=0.\n\nSo, the only possibilities are the ones given at the beginning of this answer, namely y=0 if q is not zero, and y is any real number if q=0.