Two similar cones have volumes of 8pi and 64pi find the ratios of the radio

We have that
volume larger cone=64*pi unit³
volume smaller cone=8*pi unit³

we know that
volume larger cone=[scale factor]³*volume smaller cone
[scale factor]³=volume larger cone/volume smaller cone
[scale factor]³=64*pi/(8*pi)> 8
[scale factor]=∛8> [scale factor]=2

Find the ratios of the radio 
[radio larger cone/radio smaller cone] is equal to the scale factor
so
[radio larger cone/radio smaller cone]=2
or 
[radio smaller cone/radio larger cone]=1/2

60 ÷ -20 x makes x = -3