(х²+1/х-3) - (10/х-3) = х²+1-9/х-3 = х²-9/х-3 = (х-3)(х+3)/х-3 = х+3

если х = 57, то 57+3= 60

y+7/y²-25 - (2y+2/y²-25) = y+7-2y-2/(y-5)(y+5) = - y+5/(y-5)(y+5) = - y+5