Answer: If you wanted to write 2V, then 2 is a coefficient of V, and the answer will be "none of the above"
now, suppose that V is a subset of W, or V⊂W
if the expression says 2⊂V, then 2 is a subset of V and a subset of W.
if the expression says 2 ∈ V then 2 is a element of V and a element of W
if 2 ⊂ W, then 2 is an subset of W, but not necessarily an subset of V
if 2 ∈ W, then 2 is an element of W, but not necessarily an element of V.
