1)Найдите разность: 1/8x -7x+y/8xy 2)28x^2/7x-7 -4x

1)
1/8x -(7x+y)/8xy = (y-7x-y)/8xy = -7x/8xy = -7/8y

2)
28x^2/(7x-7) -4x = 4x^2/(x-1) -4x = 4x(x/(x-1) -1) = 4x(x-x+1)/(x-1) = 4x/(x-1)