The volume of a sphere is (4/3) (pi) (radius cubed).
The volume of one sphere divided by the volume of another one is
(4/3) (pi) (radius-A)³ / (4/3) (pi) (radius-B)³
Divide top and bottom by (4/3) (pi) and you have (radius-A)³ / (radius-B)³ and that's exactly the same as ( radius-A / radius-B ) cubed.
I went through all of that to show you that the ratio of the volumes of two spheres is the cube of the ratio of their radii.
Earth radius = 6,371 km Pluto radius = 1,161 km
Ratio of their radii = (6,371 km) / (1,161 km)
Ratio of their volumes = ( 6,371 / 1,161 ) cubed = about <u>165.2</u>
Note: I don't like the language of the question where it asks "How many spheres...". This seems to be asking how many solid cue balls the size of Pluto could be packed into a shell the size of the Earth, and that's not a simple solution. The solution I have here is simply the ratio of volumes ... how many Plutos can fit into a hollow Earth if the Plutos are melted and poured into the shell. That's a different question, and a lot easier than dealing with solid cue balls.
If there are 20 and stickers are sold in 15 sheets, then you got to work backwards. take the answer and multiply it by the amount of sheets. For example: 4 times 15 is 60, 60 divided by 20 is 3. No leftover numbers.
