Answer:
83.6 mL
Step-by-step explanation:
Given 440 mL of 19% acid solution. This means the whole volume of this acid solution is 100%. Let x mL be the volume of pure acid in this solution.
Then

Write a proportion:

Cross multiply:

 
        
             
        
        
        
(5x - 2)²
Step-by-step explanation:
25x² - 20 + 4
(5x - 2)(5x - 2)
(5x - 2)²
 
        
                    
             
        
        
        
Answer: x=4 y=14 z=4
Step-by-step explanation:
On edge it is that 
 
        
             
        
        
        
I have no idea good question though 69=y