In two alloys A and B the ratio of Zinc and Tin is 5 : 2 and 3 : 4 respectively. 7 kg of the alloy A and 21 kg of the alloy B are mixed together to form a new alloy. What will be the ratio of Zinc and Tin tin the new alloy ?

Answer: Option D

	Zinc	:	Tin
A	5x	:	2x	=	7x
B	3y	:	4y	=	7y

⇒ A ⇒ 7x = 7 kg
x = 1 kg
∴ Zinc in alloy A ⇒ 5kg
Tin in alloy A ⇒ 2 kg
⇒ B ⇒ 7y = 21 kg
y = 3 kg
Zinc in alloy B ⇒ 3 × 3 = 9 kg
Tin in alloy B ⇒ 3 × 4 = 12 kg
∴ After mix - up the ratio of Zinc and Tin in new alloy
$$\begin{array}{rl}& \text{ Zinc}:\text{Tin}\\ & \text{A}5:2\\ & \text{B}9:12\\ & \overline{\text{A}+\text{B}:\text{14}\text{14}}\\ & \boxed{1:1}\end{array}$$