Find the intersection of each of the following pairs of sets

Question

c) P = {x : n ∈ N, x = 3n n< 3}

Q = {x : x ∈ N x < 7}

Answer 1

set P: x=3n where n is a natural number and n< 3, so n=1 or 2

         x=3*1=3 and x=3*2=6

     P={3,6}

set Q: x is a natural number less than 7, so x=1,2,3,4,5, or 6

     Q={1,2,3,4,5,6}

     P∩Q={3,6}=P, so P is a subset of Q