If in ∆ ABC, ∠ABC = 5 ∠ACB and ∠BAC =

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Here , ∠ABC = 5 ∠ACB and ∠BAC = 3∠ACB
We know that , ∠ABC + ∠ACB + ∠BAC = 180°

⇒ ∠ABC +	1	∠ABC +	3	∠ABC	= 180°
	5		5

⇒ ∠ABC +	4	∠ABC = 180°
	5

or	9	∠ABC = 180°
	5

⇒ 9 ∠ABC = 180 × 5
⇒ ∠ABC = 100°