Pure acid is to be added to a 10% acid solution to obtain 90L of 81% solution. What amounts of each should be used? How many liters of 100% pure acid should be used to make the solution?

Step-by-step explanation:

let X be the quantity of 100% acid

let Y be the quantity of  10% acid

X + Y = 90

Y = 90 - X

         X(100) + Y(10) = 90(81)

X(100) + (90 - X)(10) = 90(81)

   100X + 900 - 10X = 7290

                         90X = 6390

                              X = 71 L

the answer is 489

step-by-step explanation:

you can first factor out the n to get n(1+5). we know that 1+5 is 6, so we just have 6n.