How much pure acid should be mixed with 5 gallons of a 70% acid solution in order to get a 90% acid solution

Question

Homework quiz

Answer 1

Answer: 10 gallons of Pure Acid 

Step-by-step explanation:

5 gallons of Acid solution = 70% 

x gallons of Pure Acid = 100% 

5 + x gallons of Mixture = 90%

70 * 5 + 100 x = 90 ( 5 + x )

350 + 100 x = 450 + 90 x 

100 x + -90 x = 450 - -350 

10 x = 100 

/ 10 

x = 10 

10 gallons of Pure Acid 

Answer 2

0.70(5) + 1.00x = 0.90(5 + x)

Can you solve for x and answer?