SOLUTION: it is necessary to have a 40% antifreeze solution in the radiator of a certain car. The radiator now has 70 liters of 20% solution. How many liters of this should be drained and re

Question 838111: it is necessary to have a 40% antifreeze solution in the radiator of a certain car. The radiator now has 70 liters of 20% solution. How many liters of this should be drained and replaced with 100% antifreeze to get the desired strength?
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
Percent ---------------- quantity
Antifreeze 100% 100.00% ---------------- x liters
Antifreeze 20% 20.00% ------ 20 - x liters
Mixture 70.00% ---------------- 20
Total 20 liters
100.00% x + 20.00% ( 20 - x ) = 70.00% * 20
100 x + 20 ( 20 - x ) = 1400
100 x + 400 - 20 x = 1400
100 x - 20 x = 1400 - -400
80 x = 1000
/ 80
x = 12.5 liters 100.00% Antifreeze 100%
7.5 liters 20.00% Antifreeze 20%

m.ananth@hotmail.ca
The quantity you need to increase the percentage to 70 is the amount to be drained

12.5 liters has to be drained
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