Question 934141
let x = amount of acid you need to add to your solution to make it 35% acid.


your new solution will be equal to 60 + x.


you currently have 15 ml of acid because .25 * 60 = 15.


if you add x to that, you will get x + 15 ml of acid.


if you add x to 60, you will get x + 60 of total solution.


x + 15 must be equal to 35% of 60 + x in your new solution.


your equation is x + 15 = .35 * (60 + x)


simplify this equation to get x + 15 = .35 * 60 + .35 * x


subtract .35 * x from both sides of the equation and subtract 15 from both sides of the equation and you get x - .35 * x = .35 * 60 - 15.


simplify that equation to get .65 * x = 6.


divide both sides of that equation by .65 to get x = 6/.65 = 9.l230769231.


that's your solution.


you start with 15 ml of acid in 60 ml of solution.


15 / 60 = .25 which is the current ratio.


add 9.1230769231 of acid and you get 15 + 9.1230769231 ml of acid in a total solution of 60 + 9.1230769231 ml.


that simplifies to 24.1230769231 ml of acid in a total solution of 69.1230769231 ml.


24.1230769231 / 69.1230769231 = .35


your solution is now 35% acid.