A certain quantity of 40% solution is replaced with 25% solution such that the new concentration is 35%. What is the fraction of the solution that was replaced?  Choose the correct answer: A) 1/4 B) 1/3 C) 1/2 D) 2/3 E) 3/4
Original quantity = A   Substituted quantity = 1/3   Then:   (A*0.4 + 0.25*1/3 тАУ 0.4*1/3 ) / A = 0.35   0.4 + (1/3/A)*(-0.15)=0.35   1/3/A=-0.05/-0.15=1/3   ANSWER:1/3
<result>B</result>
A certain quantity of 40% solution is replaced with 25% solution such that the new concentration is 35%. What is the fraction of the solution that was replaced?