Set up help

Question

How much pure acid should be mixed with 4 gallons of a 50% acid solution in order to get an 80% acid solution

Answer 1

Let x be the amount of acid that should be mixed with 4 gallons of 50% acid, therefore the total amount of the mix is

 

x+4(0.5) , the amount of the mix should also equal to 80% acid of the total, the total amount would be 0.8(4+x)

 

the following equation can be set up   x+0.5(4)=0.8(x+4), solve for x

 

x+2=0.8 x+3.2, subtract 0.8x from both sides x-0.8x+2=0.8x-0.8x+3.2,  0.2x=3.2, x =6 

 

6 gallons of pure acid must be mixed with the 4 gallons of 50% acid to give 80% of pure acid in the solution