We know that opposite angles of a paralleloram are equal . ∴ ∠P = ∠R ⇒ 3x - 4 = 56 - 3x ⇒ 6x = 60 ⇒ x = 10 Thus, ∠P = ∠R = 3 × 10 - 4 = 26° Also, ∠P + ∠Q = 180° [adjacent angles of a parallelogram] ⇒ ∠Q = 180°- 26° = 154° Thus,∠Q = ∠S = 154° Hence, the four angles of the parallelogram PQRS are 26°, 154°,26° and 154°. We should care our earth to have good eco balance.