Chemisty
posted by George .
Alexander, who weighs 159 , decides to climb Mt. Krumpett, which is 5460 high. For his food supply, he decides to take nutrition bars. The label on the bars states that each 100 bar contains 10 of fat, 40 of protein, and 50 of carbohydrates.Alexander wants to know exactly how many bars to pack in his backpack for the journey. To provide a margin of safety, he assumes that he will need as much energy for the return trip as for the uphill climb. How many bars should Alexander pack?
How would I even go about solving this problem?

The problem is silly, it assumes 100 percent efficiency in converting food energy to gravatational PE. On the other hand, it is going to ask you to forget about the loss of graviational PE on the trip down.
energy=2mgh
this is energy in joules, convert to calories.
Then, convert the fat protein and carbs to food calories, thence to real calories. solve for the number of bars. 
Is it 450 calories I don't know what you mean by 2mgh