If we assume that your mass is m kilograms, then you would need to eat 80 times your mass in food each day. Therefore, you would eat:
80m kilograms of food per day
To find how much you would eat in a month, we need to multiply the amount of food you eat in a day by the number of days in a month. We'll assume a month has 30 days.
Number of kilograms of food eaten per month = Number of kilograms of food eaten per day x Number of days in a month
= 80m x 30
= 2400m
Therefore, you would eat 80m kilograms of food per day and 2400m kilograms of food per month.