How much pure alcohol must be added to 400 ml of a 15% solution to make its strength 32%

Quantity of alcohol =400*15/100 = 60ml
x is pure alcohol which must be added : (x + 60)/(x + 400) = 32/100
100x + 6000 = 32x + 12800 => 68x = 6800 => x = 100
100ml pure alcohol must be added

1. isolate the variable, in this case, d. subtract 35.5 on both sides of the equation.2. 52 subtracted by 35.5 is 16.53. therefore your answer would be d= 16.5this is the basics of pre algebra, isolating variable through adding, subtracting, multiplying, and dividing, if you have any other questions to ask just comment!