A = {Triangles, Quadrilaterals, Pentagon, Hexagon, Heptagon}
B = {Triangles};
C = {Quadrilaterals}
i) A ∩ B = {Triangles, Quadrilaterals, Pentagon, Hexagon, Heptagon} ∩ {Triangles} = {Triangles}
ii) A ∩ C = {Triangles, Quadrilaterals, Pentagon, Hexagon, Heptagon} ∩ {Quadrilaterals} = {Quadrilaterals}
iii) A-B = {Triangles, Quadrilaterals, Pentagon, Hexagon, Heptagon} – {Triangles} = {Quadrilaterals, Pentagon, Hexagon, Heptagon}
iv) A – C = {Triangles, Quadrilaterals, Pentagon; Hexagon, Heptagon} – {Quadrilaterals}
= {Triangles, Pentagon, Hexagon, Heptagon}