How do I rearrange this for y?
In fact what you want is not clear
It may be written as
log 10y - 3 lof 10x = 2
log (10y)/( 1000 x ^3) = 2
If the log is to the base 10 then we have
(10y)/( 1000 x ^3) = 10 ^ 2 etc please be specific with your question so as to enable us to help and avoid guess work