Question

[Nguyễn Phan Thục Trinh]

a) \(x^{n+1}y:3x^3y^{n-1}\)

b) \(\left(a+b\right)^{5n}.\left(a-b\right)^7:\left(a+b\right)^{15}.\left(a-b\right)^n\)

c) \(\left(21x^2y^3+9x^4y^2+7x^5y^3\right):7x^{n+1}y^{n+1}\)