M density.....?

density equals m divided by volume so take .0015 and set it equal to m/v. do the same for .0020. you need to know the volume of the flasks though to finish the problem. they will be the same since they are identical but lets say the volume was 2. Take the density of each and multiply by 2 (cross-multiplying) and that will give you your m. Do the same for flask b. All you need is your volume fo the flasks. sorry, hope i could help!