Question 310584
A car radiator has a 6-liter capacity.
 If the liquid in the radiators 40% antifreeze,
 how much liquid must be replaced with pure antifreeze to bring the mixture up to a 50% solutions? 
:
 x = amt to be removed
 and
 x = amt of pure antifreeze required to replace it
:
.40(6-x) + x = .50(6)
:
2.4 - .4x + x = 3
:
-.4x + x = 3 - 2.4
:
.6x = .6
x = {{{.6/.6}}}
x = 1 liter removed and 1 liter of pure antifreeze added