Cho A = {x ∈ X | x = 2k - 3; k ∈ N; k ≤ 3}; B = {x ∈ R | (x - 3)(x - 9)(x - 27) = 0}; C = {3;5;7;9;15;27}. Tìm A ∩ B; A ∪ B; A \ B

Cho: 
$$\begin{gathered} A=\left\{x\in Z|x=2k-3,k\in N,k\le 3\right\} \\ B=\left\{x\in R\left|\right(x-3\left)\right(x-9\left)\right(x-27)=0\right\} \\ C=\left\{3,5,7,9,15,27\right\} \\ Tìm: \\ a. A\cap B, A\cup B, A\backslash B \\ b. Tìm X biết (A\cap B)\subset X\subset A \\ c.Tìm Y biết E\backslash Y=\left\{3,5,7\right\} ; Y\backslash E=\left\{30\right\} \end{gathered}$$