3 × tan (x – 15) = tan (x + 15)⇒ tan(x + 15) / tan(x – 15) = 3/1⇒ {tan (x + 15) + tan (x – 15)} / {tan (x + 15) – tan (x – 15)} = (3 + 1) / (3 – 1)⇒ {tan (x + 15) + tan (x – 15)} / {tan (x + 15) – tan (x – 15)} = 2⇒ sin(x + 15 + x – 15) / sin(x + 15 – x + 15) = 2⇒ sin 2x / sin 30 = 2⇒ sin 2x / (1/2) = 2⇒ 2 × sin 2x = 2⇒ sin 2x = 1⇒ sin 2x = sin 90⇒ 2x = 90⇒ x = 45