The best way would be to weigh it and then weigh out tenths.
Otherwise you could note that 1 cup is 240 ml and one tenth of that is 24 ml. Since salt is not a liquid I think the weight idea works MUCH better.
Three and five tenths divided by three and four tenths is 1.0294.
2
8 and 4/7
one
6/10 divided by 7/10 is 0.857142857142857
seven tenths
Not by itself. A cup of salt may be a fraction of the total amount of salt in the world, but just sitting there, a cup of salt is a cup of salt.
0.3478
0.625
I don’t know
Four tenths of a cup is equivalent to 0.4 cups. This can also be expressed as 40% of a cup, which is equal to 6.4 tablespoons or about 1.92 fluid ounces.
1/5 of a cup. duhhhh