If a dna molecule is made up of 30% thymine what percent of it would be guanine

20% would be guanine.

All 4 bases must equal 100.

30 thymine+30 adenine=60

100-60=40 of guanine and cytosine

40÷2=20 is just guanine

this is more of a statement than a question. is there answers to go along with this, or is it opinion based?

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.