let
A------------> smaller sphere
B----------> larger sphere
radius of sphere A-------> rA
radius of sphere B----> rB
we know that
rA/rB=8/9
the scale factor is equal to 8/9
volume smaller sphere A=[scale factor]³*volume larger sphere B
volume smaller sphere A/volume larger sphere B=[scale factor]³
volume smaller sphere A/volume larger sphere B=[8/9]³----> 512/729
the answer is
512/729