Translate each of these nested quantifications into an English statement that expresses a mathematical fact. The domain in each case consists of all real numbers. a)∃x∀y(x + y = y) b)∀x∀y(((x ≥ 0) ∧ (y < 0)) → (x − y > 0)) c)∃x∃y(((x ≤ 0) ∧ (y ≤ 0)) ∧ (x − y > 0)) d)∀x∀y((x ≠ 0) ∧ (y ≠ 0) ↔ (xy ≠ 0))