There are 150 fifths in a 750 ml bottle. This is because there are 5 ml in a fifth and 750 divided by 5 equals 150.
750 divided by 50 = 15
Say you had 750+-15. You would do 15 divided by 750 equals .02. Then multiply be 100 to turn it into a percentage and you get 2%.
0.375
750
187.5
400000
0.0027
250
750
750
750