algebra
posted by juan on .
A pharmacist has 40% and 60% iodine solutions on hand. How many liters of each iodine solution will be required to produce 4 liters of a 50% iodine.

.4x + .6(5x) = .5(4)
x=5
so, 5L of 40% and 5L of 60%
makes sense, since 50% is halfway between the two.