We have been getting numerous questions like this on assignments and I can't figure them out. Its like I know that there some way connected but I can't figure it out. This is for Chemistry in highschool and its likea review and so they are not going over it but I would still like to know how to do them for future reference. This is the question:

Question

A solution containing 50.64 mL of liquid A and 36.22 mL of liquid B has a density of 1.0472 g mL-1. On adding a further 34.82 mL of liquid B to the mixture, the density drops to 0.9558 g mL-1. Assuming that the volumes are additive, calculate the density of liquid B in g mL-1.

Now I thought you would just find the mass of solution 1 and the mass of solution 2 using d=m/v and then subtract them to get the resulting mass and then use d=m/v with the volume that was added and get the answer but it clearly does not work. And I've tried like adding them together and random thingsand I'm just stuck. Thanks for your help.

You might try posting your work so we can see it. And do you have an answer from the book you are trying to get? If so post that, too. Check for typos in the post, also.