[(-4a^2b^3c)^2/(-2ab^2)](-ab)^2/(4a^3b^4c^2)
=16a^4b^6c^2×a^2b^2/[-8a^4b^6c^2]
=-2a^6b^8c^2/[a^4b^6c^2]
=-2a²b²
2.
(-2a^2b^3c)^2(2a^2c^2)/（-6a^3b^3c)/(3ab^3c^3)
=4a^4b^6c^2*2a^2c^2×3ab^3c^3/(-6a^3b^3c)
=12a^7b^9c^7/(-6a^5b^3c)
=-2a^4b^6c^6
=-162b^6c^6