(x+2/x+1) - (x+3/x-2) - (x-4/x-3) + (x-5/x-4)
=x+2/x+1 - x-3/x+2 - x+4/x+3 + x-5/x-4
=(x-x-x+x)+(2/x-3/x+4/x-5/x)+(1+2+3-4)
=-2/x + 2