[ranij]

A certain quantity of 40% solution is replaced by a 25% solution sch that the new concentration ratio is 35% What is the ration of solution that was replaced to the ratio of the solution that was not replaced?

[ebaines]

You need to set up an equation that represents the word problem:

"A certain quantity of 40% solution": if we let Q = the quantity of solution, then the amount of "stuff" in this solution is 0.4Q.

"is replaced by a 25% solution": hence an amount x of the solution is removed and new 25% solution replaces it, so the total amount of "stuff" in solution is now: 0.4(Q-x)+0.25x

"such that the new concentration ratio is 35%": the total amount of liquid is still Q, but at 35% concentration, so:
0.4(Q-x)+0.25x = 0.35Q

Now you can solve for x, and find the ratio of x/Q.

Post back with your answer and we'll check it for you.