x+2 ∈ D50={1,2,5,10,25,50}/-2
x∈{-1,0,3,8,23,48}
3/x => x∈M3={0,3,6,9,12,18,21,24..}
A={0,3,48}
2x+3∈D18={1,2,3,6,9,18,}/-3
2x∈{-2,-1,0,3,6,15}/:2
x∈{-1,-1/2,0,3/2,3,15/2}
x∈N => B={0,3}
4≤2x<10/:2
2≤x<5 => x∈{2,3,4}
2x+1∈D7={1,7}/-1
2x∈{0,6}/:2
x∈{0,3} =>C={3}