NEED SOME HELP WITH MATH PROBLEM:
the cooling system of a car has a capacity of 20 liters. If the system is currently filled with a mixture that is 20% antifreeze, how much of this mixture should be drained and replaces with pure antifreeze so that the system is filled with a solution that is 40% antifreeze?

Question

NEED SOME HELP WITH MATH PROBLEM:
the cooling system of a car has a capacity of 20 liters. If the system is currently filled with a mixture that is 20% antifreeze, how much of this mixture should be drained and replaces with pure antifreeze so that the system is filled with a solution that is 40% antifreeze?

anonymous · Answer

The equation (pure antifreeze would be 1a)
.40(15-a) + a = .50(15)

anonymous · Answer

Okay so what would i plug in for a

anonymous · Answer

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CCsQFjAA&url=http%3A%2F%2Fwww.algebra.com%2Falgebra%2Fhomework%2Fword%2Fmixtures%2FMixture_Word_Problems.faq.question.400904.html&ei=M6o4UvqGBeXS2QWUooCIBw&usg=AFQjCNHmj01mg0htVXEUnGXsnD1_AZcORA&bvm=bv.52164340,d.b2I

anonymous · Answer

and whre did you get 15 from @jonjenkins7653