I dont understand this at all.

They are the same.

Step-by-step explanation:

The volume of the hemisphere is V = ⅔ π r³.

The cone's height is equal to its radius, so its volume is:

V = ⅓ (π r²) (r)

V = ⅓ π r³

The cylinder's height is equal to its radius, so its volume is:

V = (π r²) (r)

V = π r³

So the total volume on the left side is ⅔ π r³ + ⅓ π r³ = π r³.

The total volume on the right side is π r³.

The volumes are equal, and since all are made of the same material (have the same density), the masses are also equal.