realistically that sort of thing needs to be discussed with your care provider.
Insulin can be harmful to your health ( hypoglycaemia or hyperglycaemia ) if too much or too little is taken.
other factors such as your weight and insulin sensitivity ( or resistance ) come into play as well.
perhaps I can explain a bit more about Novomix 30 to see if that will help you understand.
this insulin is made up of 30% short acting and 70% long acting insulin in a mix.
taking 10 units of novomix 30 means that 3 units fast acting is delivered -- and a starting ratio for many doctors is 1 unit for 10 carbs , so in theory a 10 unit dose would require you to eat 30 grams of carbohydrate.
but in truth you do really need to check with your doctor