SOLUTION: How many liters of pure antifreeze must be added to 30 liters of a 60% solutions to obtain a 75% solution? I have the problem down but forgot how to get the second number where

Question 262056: How many liters of pure antifreeze must be added to 30 liters of a 60% solutions to obtain a 75% solution? I have the problem down but forgot how to get the second number where you go to the second box and subtract a question mark. HELP ME!
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
How many liters of pure antifreeze must be added to 30 liters of a 60% solutions to obtain a 75% solution? I have the problem down but forgot how to get the second number where you go to the second box and subtract a question mark.
:
I don't know about the box or the question mark, but here is how I would do it
:
let x = amt of pure antifreeze to be added:
then
(x+30) = the final amt
:
.60(30) + 1.0x = .75(x+30)
18 + 1x = .75x + 22.5
1x - .75x = 22.5 - 18
.25x = 4.5
x =
x = 18 liters of pure antifreeze required
:
:
Check solution:
.6(30) + 18 = .75(18 + 30)
18 + 18 = .75(48)
36 = 36; confirms our solution
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