<PRE><B>Question 272808</B>
An automobile radiator is full of a 20% antifreeze solution.
 If its capacity is 12 quarts, how many quarts must be replaced by a 95% solution to give 12 quarts of a 70% solution?
:
Let x = amt to be replaced
:
.20(12-x) + .95x = .70(12)
2.4 - .2x + .95x = 8.4
-.2x + .95x = 8.4 - 2.4
.75x = 6
x = {{{6/.75}}}
x = 8 qts of 20% solution removed and 8 qts of 95% solution to be added</PRE>