Так понятно или надо написать?

1) (x/(x - 1) - 1) * (xy - y)/x

(x/(x - 1) - 1) = (x - (x - 1))/(x - 1) = -1/(x - 1)

(xy - y)/x = y(x - 1)/x

-1/(x - 1) * y(x - 1)/x = -y/x

Ответ: -y/x

2) a/b - (a² - b²)/b² : (a + b)/b

(a² - b²)/b² : (a + b)/b = (a² - b²)/b² * b/(a + b) = ((a -b)(a + b))/b² * b/(a + b) = (a - b)/b

a/b - (a - b)/b = (a - a - b)/b = -b/b = -1

3) ((y + 3)/(y - 3) - (y - 3)/(y + 3)) : 12y/(y₂ + 6y + 9)

((y + 3)/(y - 3) - (y - 3)/(y + 3)) = ((y + 3)² - (y - 3)²)/(y + 3)*(y - 3)

((y + 3)² - (y - 3)²)/((y - 3)/(y + 3)) = (y² + 6y + 9 - y² + 6y - 9)/(y + 3)*(y - 3) = 12y/(y + 3)*(y - 3)

12y/(y + 3)*(y - 3) : 12y/ (y + 3)² = 12y/(y + 3)*(y - 3) * (y + 3)²/12y = (y + 3)*(y - 3) / (y + 3)² = y - 3