Question 1024647
she wants to get a mix of 5% minoxidil.


she has 80 ml of 2% solution of minoxidil.


she has a certain quantity of 7% minoxidil solution on hand that she can use.


let x equal the amount of 7% solution that she has to add.


let y = the total amount of solution that she will wind up with.


you have two equations that need to be solved simultaneously.


they are:


total solution:


80 + x = y


total amount of minoxidil:


.02 * 80 + .07 * x = .05 * y


since y = 80 + x, then replace y with 80 + x in the second equation to get:


.02 * 80 + .07 * x = .05 * (80 + x)


simplify this equation to get:


1.6 + .07 * x = 4 + .05 * x


subtract 1.6 from both sides of the equation and subtract .05 * x from both sides of the equation to get:


.07 * x - .05 * x = 4 - 1.6


simplify to get .02 * x = 2.4


divide both sides of the equation by .02 to get x = 2.4 / .02 = 120.


she would need 120 ml of the 7% solution to get a 5% solution.


the total number of mls would be 80 + 120 = 200.


the total amount of minoxidil would be .02 * 80 + .07 * 120 = 1.6 + 8.4 = 10.


the percent of minoxidil in the final solution would be 10 / j200 = .05 * 100 = 5%.