cost of wine bottle to drink = $30
monthly budget for drinking = $300
consumption/week = 2 bottles
consumption/month = 10 bottles
gift/month = 2 bottles
cost per month = (10 consumption + 2 gift ) x 30 = 360 → -2 deficit → drink from investment bottles → can't sell 120 in the 5th year
your calculation is wrong because you overlooked the gift part. otherwise its not bad. just a silly mistake but a consultant case should be of a good quality no?