`a)`
Để `A ⊂ B`
`<=>` \(\left\{ \begin{array}{l}m ≥ 4\\m + 4 ≤ 7\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}m ≥ 4\\m ≤ 3\end{array} \right.\)
`=> A ⊄ B`
`b)`
Để `A cap B = ∅`
`<=>` \(\left[ \begin{array}{l}m > 7\\m + 4 < 4\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}m > 7\\m < 0\end{array} \right.\)
`=> m in (-∞; 0) cup (7; +∞)`