а)28ab²/9c³ * 18c⁵/35a²b = 56bc² / 35a
б)(x²-4y²) : x+2y/2y = (x-2y)(x+2y) * 2y / x+2y = 2y(x-2y)
в)8m-2n/2n+3 * 9+6n/32m²-2n² = 2(4m-n) \ 2n+3 * 3(3+2n) \ 2(4m-n)(4m+n) = 3 \ 4m+n
г)y+6/y²-12y+36 : 6y+36/y³-6y² = y+6 \ (y-6)² * y²(y-6) \ 6(y+6) = y²\6