Question

The empty relative density bottle weight 40g .The bottle weight 80g when filled with methylated spirit and 90g when filled with water. Find the density of methylated spirit. (density of water=1000kg/millimeters cube

Answer 1

First millimeter is not correct. Do you mean 1000 kg/mL? mm is a distance, not a volume. And 1000 kg/mL is REALLY large. I think you mean 1000g/mL for the density of water.
Please repost and get the numbers and units right. I don't want to guess at an answer.