Is this correct?

Question

subtract (4a^3+2b^3)-(6a^3+5a^2b-2ab^2+2b^3)

answer: -2a^3-5a^2b+2ab^2

Answer 1

correct

Answer 2

(2b^3-5b^2+3ab)(-3b^2)

Answer 3

[(-1/3a^2b^3c)^2*(-9/2ab^2c^2)+(+3/5a^4b^5c^3)^2:(-3/5a^3b^2c^2)]^2:(+11/10a^2b^8c^4)