[(-3x²y∧4)²·x²-2x(3x²y²)³·1/3y²]÷9x∧7y∧8
=(-3x^6y^8-18x^7y^4)÷9x^7y^8
=-1/3x^(-1) - 2y^(-4)
=1/3x - 2/y^4