How to solve this chemistry problem?

I am a chemist for 6 years till now:

The solution is:

The person weight is 170 lb which fat make 14% of this weight. By multiply 170 lb by 14% we get that 14% represents 23.8 lb, i.e the person's body contains 23.8 lb fats.

From the problem's data: 1 lb provide 4500 kcal, and we have 23.8 lb, multiply 4500 kcal/1 lb by 23.8 lb, we can get the all the energy given when the whole body fat content "23.8 lb" burned and converted into energy which equal (=107100 kcal).

From the given data in this problem: the body consume 2000 kcal in the whole day, and we have a storage of 107100 kcal, divide the whole energy available on the energy quantity need per day, (107100 kcal÷ 2000 kcal/1 day=53 day).

by take in account the solution of this problem, we can say that if the person's body have the body fats as the only energy source, the fats will deplete completely within 53 days.

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