Amolecule that can be used as a molecular clock has a neutral mutation rate of one mutation per 5 million years. how many years ago did two species share a common ancestor if the molecules found in these two species differ by a total of eight mutations?

x would be the most and the least would be y because there are more fruit   and seeds than flock z has insects

they had the law tat factories that produces smoke cannot be built near residential buildings.

building of proper sewage system was done to ensure that the waste is carried away from the humans so that they do not get diseases from it.

also they built water systems to provide water in those areas which are drought prone.