A pharmacist wishes to mix a solution that is 6% Minoxidil. She has on hand 100 ml of a 2% solution and wishes to add some 8% solution to obtain the desired 6% solution. How much 8% solution should she add?
She should add
ml.

200 ml

Step-by-step explanation:

It's proportions basically.

frst off, 2% of 100 ml is 2 ml, so the 100 ml solution has 2 ml of Minoxidil.

Eventually we want 6/100 to be the porportion.  so the total is going to be 100 (from the initial 100 ml) plus however much is needed x.  And we want the amount of Minoxidil to be 2 + 8 percent of x.  so this gets us the equation

6/100 = (2 + .08x)/(100+x)  Then we solve

(100 + x) 6/100 = 2 + .08x

(100 + x) 6 = 200 + 8x

600 + 6x = 200 + 8x

400 = 2x

x = 200

so they should add 200 ml

You can check too.  there is 100 + 200 ml of solution total and 2 + 16 ml of Minoxidil so that's 18/300 = 6/100

its a straight line parallel to the time axis