Question 903694
30 liters of milk at 2 liters for $1.40 is worth 30 * $1.40 / 2 = $21.00


your cost per liter is equal to $21.00 / 30 = $.70 per liter.


You want your mixture to be worth $.50 per liter.


let x = the number of liters of water you need to add.


you want .50 * (x + 30) = $21.00


that's x + 30 liters of milk and water at $.50 per liter is equal to $21.00 which is the same value as 30 liters of pure milk milk at $.70 per liter.


your formula is:


$.50 * (x + 30) = $21.00


simplify to get:


$.50 * x + $15.00 = $21.00


subtract $15.00 from both sides of this equation to get:


$.50 * x = $6.00


divide both sides of this equation by $.50 to get:


x = 12


you need to add 12 liters of water to get a mixture with a value of $21.00.


total liters required = 30 milk + 12 water = 42 liters of mixture.


$.50 * 42 = $21.00 for 42 liters of milk and water mixture.