let A={1,2,3,4} B={1,2,3} C={2,4} find all sets X such that X is a subset of B but not of C

let A={1,2,3,4} B={1,2,3} C={2,4} find all sets X such that X is a sub

1.	let A={1,2,3,4} B={1,2,3} C={2,4} find all sets X such that X is a subset of B but not of C
Answer» Please give explanation Ans is {1,3}