how much of alcohol is 20ml in 100ml blood?

20 mL of alcohol in 100 mL of blood would be 20% alcohol by volume. That is because:

• 20÷100=0.2020\div 100=0.2020÷100=0.20
• 0.20=20%0.20=20%0.20=20%

For context, blood alcohol content is usually reported as grams of alcohol per 100 mL of blood , so a value like 20 mL per 100 mL is not the usual medical way of expressing BAC.

If you meant 20 mg instead of 20 mL, the result would be very different.