Answer :
Answer:
- He must use 50g of the 12% solution and 30 g of the 20% solution.
Explanation:
Call x the amount of 12% boric acid solution to be used.
- The content of acid of that is: 0.12x
Since he wants to make 80 grams of solution, the amount of 20% boric acid solution to be used is 80 - x.
- The content of acid of that is{ 0.20(80 - x).
The final solution is 15% concentrated.
- The content of boric acid of that is 0.15 × 80 g.
Now you have can write your equation:
[tex]0.12x+0.20(80-x)=0.15\times 80[/tex]
Solve:
[tex]0.12x + 16 - 0.20x=12\\\\-0.08x=12-16\\\\0.08x=4\\\\x=4/0.08\\\\x=50[/tex]
That is 50 grams of the 12% solution of boric acid.
Calculate the amount of the 20% solution of boric acid:
[tex]80-x=80-50=30[/tex]
That is 30 grams.
Then, he must use 50g of the 12% solution and 30 g of the 20% solution.