20% acid solution is mixed with a 70% acid solution to get 50 liters of a 40% solution.

How much of the 70% solution is used?

Question

20% acid solution is mixed with a 70% acid solution to get 50 liters of a 40% solution.

How much of the 70% solution is used?

hero · Answer

Hint: 

x + y = 50
.20x + .70y = 20

hero · Answer

Solve the system and find y

hero · Answer

Chero, you there?

anonymous · Answer

yes

anonymous · Answer

sorry. I am doing something wrong because I am getting y=28.57-20x/.70

hero · Answer

1. Isolate x in each equation
x = 50 - y 
x = (20 - .70y)/.20

1. Set x = x
x = x
50 - y = (20 - .70y)/.20

2. Cross multiply: 
.20(50 - y) = 20 - .70y

3. Simplify and solve for y: 
10 - .20y = 20 - .70y
.70y - .20y = 20 - 10
.50y = 10
y = 10/.50
y = 20

Since y represents the 70% solution, 20 liters of that solution was used.

anonymous · Answer

THank you soooo much! I've being doing math since 10 am this morning! Tomorrow is our last day to finish this stuff so I really appreciate your help!!! I am just about fried!

hero · Answer

You've been doing math since 10am for your son?