Hello
In the left picture, you can read the volume of water (only water) V₁=15 mL.
In the right picture, you can read the volume of water add with the brown thing. You can call it V₂ = 24 mL.
So, the volume of the brown thing is V₂ -- V₁ = 24 - 15 = 9 mL
I hope it's the good question I answered :)
