SOLUTION: A chemist has two solutions. one has 40% the other 25% concentrate. how many liters of each solution must be mixed to obtain 129liters of 34% solution?? I missed class yesterday

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: A chemist has two solutions. one has 40% the other 25% concentrate. how many liters of each solution must be mixed to obtain 129liters of 34% solution?? I missed class yesterday      Log On


   



Question 403224: A chemist has two solutions. one has 40% the other 25% concentrate. how many liters of each solution must be mixed to obtain 129liters of 34% solution??
I missed class yesterday n today n this question is on my homework n i have no idea how i would set it up. plz help....

Found 2 solutions by josmiceli, lwsshak3:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Lt a = liters of 40% solution needed
Let b = liters of 25% solution needed
In words:
(total liters of concentrate)/(total liters of solution) = 34%
given:
(1) a+%2B+b+=+129
(2) %28.4a+%2B+.25b%29%2F129+=+.34
-------------------------------
From (2):
(2) .4a+%2B+.25b+=+43.86
Multiply both sides by 100
(2) 40a+%2B+25b+=+4386
Multiply both sides of (1) by 25
and subtract from (2)
(2) 40a+%2B+25b+=+4386
(1) -25a+-+25b+=+-3225
15a+=+1161
a+=+77.4
and, from (1),
b+=+129+-+77.4
b+=+51.6
77.4 liters of the 40% solution and 51.6 liters
of the 25% solution are needed
check answer:
(2) %28.4a+%2B+.25b%29%2F129+=+.34
(2) %28.4%2A77.4+%2B+.25%2A51.6%29%2F129+=+.34
You can do the math to check answer




Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
A chemist has two solutions. one has 40% the other 25% concentrate. how many liters of each solution must be mixed to obtain 129liters of 34% solution??
I missed class yesterday n today n this question is on my homework n i have no idea how i would set it up. plz help....
..
let x=liters of 40% concentrate
then 129-x = liters of 25% concentrate
.4x+.25(129-x)=.34(129)
.4x+.25(129)-.25x=.34(129)
.15x=.34(129)-.25(129)
.15x=129(.34-.25)
x=129(.09)/.15
x=77.4 liters
129-x=129-77.4=51.6 liters
ans: 77.4 liters of the 40% concentrate and 51.6 liters of the 25% concentrate must be mixed to obtain 129 liters of 34% solution.