Trivially, if U and V are two subspaces of W

Trivially, if U and V are two subspaces ofW , then dim (U ) = dim (V ). Combine this fact, Theorem PSSD, and Theorem EDYES all into one grand combined theorem. You might look to Theorem PIP for stylistic inspiration. (Notice this problem does not ask you to prove anything. It just asks you to roll up three theorems into one compact, logically equivalent statement.)