a : b : c = 2 : 3 : 4 and 2a - 3b + 4c = 33, then the value of c is = ?

$$\eqalign{ & a:b:c \cr & 2:3:4 \cr & {\text{Let }}2x:3x:4x \cr & \Rightarrow 2a - 3b + 4c = 33 \cr & \Rightarrow 2 \times 2x - 3 \times 3x + 4 \times 4x = 33 \cr & \Rightarrow 4x - 9x + 16x = 33 \cr & \Rightarrow 11x = 33 \cr & \Rightarrow x = 3 \cr & \therefore {\text{c}} \Rightarrow 4 \times 3 = 12 \cr} $$