Everclear 151 proof 375 ml bottle - how much distilled water to make it to either 80 or 100 alcohol

A friend purchased everclear 151% proof 375 ml bottle from Florida for me.

I would like to make tincture for the first time if I receive my herbs in time on Wednesday February 22nd (new moon). I am in Canada. I guess I can either start mixing my herbs in the morning or evening???

How much distilled water can I add to make it to either 80 proof (may be use this to make dried red savina habanero pepper tincture) or 100 proof for herbs with roots....

I also have 1.75 litres of Clear Spring 190 proof bottle. If I dilute it with equal amount of distilled water it would be 95% alcohol but in order to make it to 100 alcohol I do not know how to calculate this.

Thank you for your help.

rosycheeks