Density, volume, and mass question?

Question

Substance A has a density of 1.6 grams/mL and Substance B has a density of .5 grams/mL.

If you put 10.0 mL of A into one balance pan, how much mass of B would you need in the other pan to make it balance? Why?

If you put 35.0 mL of B into one balance pan, what volume of A would you need to make it balance? Why?

I have absolutely no clue how to do this. In the first question, I found the mass of the 10 mL to be 16 but then I got totally stuck. Please help.

Answer 1

so you found the first mass to be 16... so set the mass of B to 16 to find out how much mL you need to make it balance. m/d = v

for the 2nd one... first find the mass of B

m = d/v = 35 mL/0.5 g/mL = 17.5 g

now to find volume of A.. v = m/d = 17.5 g /1.6 g/mL = 10.9 mL