You need to divide the 6 by 15 in order to get 0.4.
Ratios, fractions, decimals, and percentages are all pretty much each other, as ratios are just fractions but sideways with the colon in between the numbers. Ratios are to show a relationship, as well as the others. Fractions and ratios are decimals, as you can just simplify them into decimals. Percentages are just decimals but with the decimal moved over to the left twice. So 0.43 becomes 43%.
