How many liters of a 40% acid solution must be added to 12 liters of a 20% solution to obtain a 25% solution

Question

this is a alegbra 1 question and is a chapter 2 test form 2a question .

Answer 1

acid in 20 % solution is 2.4 in 12 liters

acid in 40 % solution is 0.4 in 1 liter

 

x = number of liters to be added

 

(2.4 + 0.4 * x) / (12 + x) = 25% or 1 / 4

 

(2.4 + 0.4 * x) / (12 + x) = 1 / 4

 

Cross Multiply

(2.4 + 0.4 * x) * 4 = 12 + x

 

9.6 + 1.6 * x = 12 + x

 

0.6 * x = 2.4

 

x = 4 liters ANSWER

 

Final solution will be 16 liters, and contain 2.4 + 4 * 0.4 liters of acid = 4 liters of acid in 16 liters of solution or 25 %