Apharmacist has an 18% alcohol solution and a 40% alcohol solution. how much of each should he mix together to make 10 liters of a 20% alcohol solution?

X = amount of the 18% solution

y = amount of the 40% solution

we know the 18% solution has only 18% of alcohol, the rest is maybe water or something, now, how many liters is 18%?  well, 18% of anything is just (18/100) * anything, so, 18% of x is just (18/100) *x or 0.18x, and that's how many liters are there.

likewise, how many liters are there in the 40% solution?  well, (40/100) * y, or 0.4y, that many.

we know the mixture has to yield 10 liters at 20% alcohol, how many liters of only alcohol is that?  well, (20/100) * 10, or 2 liters.





how much of the 40% solution?  well y = 10 - x

Where are the functions?

He will need 2,898 pieces of paper