Question 1013544
.
A Chemist has 100g of 25% acid solution. How much of these solution he needs to drain and replace 
with 70% acid solution to obtain 100g of 60% acid solution
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



        Calculations in the post by @lwsshak3 are incorrect and lead to wrong answer.

        I came to bring a correct solution.



Let x = the amount of 25% solution to drain and replace with 70% solution (in grams).
The balance equation for the acid is
0.25*(100-x) + 0.7x = 0.6*100
25 - 0.25x + 0.70x = 60
0.45x = 35
x = 35/0.45 = 77 {{{7/9}}} grams, &nbsp;&nbsp;or &nbsp;&nbsp;77.7778 grams, approximately.    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<U>ANSWER</U>


Solved correctly to teach you in a right way.