(-2/3a^4b^3c^2)^3 : (-1/3a^2bc^3)^2

( - 2/3a⁴b³c² )³ = - 8/27a¹²b⁹c⁶( - 1/3a²bc³ )² = 1/9a⁴b²c⁶( - 8/27a¹²b⁹c⁶ ) : ( 1/9a⁴b²c⁶ ) = - 8/3a⁸b⁷ = - 2 2/3a⁸b⁷