Apharmacist has 40% and 80% iodine solutions on hand .how many liters of each iodine solutions will be required to produce 6 liters of a 50% iodine mixture?

So... let's change the concentration percentage to decimal format. .. so 40% is just 4/100 or 0.4  and so on.



so... whatever "x" and "y" may be, we know the must add up to 6 liters.

and whatever 0.4x and 0.8y are, we also know, they must add up to a 3 of concentrated amount.

thus    

solve for "x", to see how much of the 40% solution will be needed.

what about "y"?  well, y = 6 - x.

Google it that might work