1. The problem statement, all variables and given/known data 150g of a solution which is 20% sulphuric acid (by mass) are added to x grams of a solution which is 70% sulphuric acid (by mass). What must be the value of x so that the final mixture shall contain 30% sulphuric acid (by mass)? 2. Relevant equations a/b=c/d ? Not sure...this is my problem. 3. The attempt at a solution I've tried equivalency calculation and any other ratio calculation that I could think of...all to no avail. I know that 30g of the original solution is SA and 120g is water. So know I need to raise that concentration (mass SA to mass Water) by 10% with a 70% solution. Where do I get started?