Question 942336
How many pints of pure antifreeze must be added to 20 pints of a 15% antifreeze solution(antifreeze and water) to make a 40% antifreeze solution?
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let x=amt of pure antifreeze must be added
15%*20+x=40%(20+x)
3+x=40%(20+x)
3+x=8+0.4x
0.6x=5
x=8 1/3 
amt of pure antifreeze must be added=8 1/3 pints