\(P=\left\{x\inℕ|x< 7\right\}\)
\(\Rightarrow P=0;1;2;3;4;5;6\)
\(Q=\left\{x\inℕ|2< x< 9\right\}\)
\(\Rightarrow Q=3;4;5;6;7;8\)
\(P=\left\{x\in N/x< 7\right\}\)
\(=>P=\left\{0,1,2,3,4,5,6\right\}\)
\(Q=\left\{x\in N/2< x< 9\right\}\)
\(Q=\left\{3,4,5,6,7,8\right\}\)