If a : b : c = 2 : 3 : 4 and 2a –3b + 4c = 33, then the

a : b : c = 2 : 3 : 4

∴	a	=	b	=	c	= k (let)
	2		3		4

⇒ a = 2k, b = 3k, and c = 4k
Given 2a – 3b + 4c = 33
⇒ 2 × 2k –3×3k + 4 ×4k = 33
⇒ 4k –9k + 16k = 33

⇒ 11k = 33 ⇒ k =	33	= 3
	11

∴ c = 4k = 4×3 = 12