How many millimeters of 30% acid solution need to be added to 60ml of 55% acid solution to get a solution that is 45% acid

So.. first off.. let's keep in mind that if 30% of acid is there in a solution, say the solution is some amount of liquid and 30% of that total liquid only is the acid, so if the amount of the liquid is say "x", then 30% of that is just (30/100) * x, or 0.3x.

now, we'll do the same for the 55% and the 45%, use the decimal format to get how much quantity in the substance is of acid.



now, whatever "x" and "y" are, we know that x + 60 = y, and we also know that 0.3x + 33 = 0.45y.