Need help to do this understand the steps too please

Question

An adult female who weighs 164 lb  consumes on average 3.210 x 10^3  . If she wants to lose  30.0 in 499 days, what should her daily caloric intake (Calories per day) be to achieve this weight loss?

Answer 1

To answer this question as written, a couple of assumptions must be made:

First, that the individual is now maintaining weight on 3210 Kcal per day,

Second, that the individual only wishes to lose fat, not water, and not bone or muscle.

30.0 lb/499 days x 3500 Kcal/1 lb fat = approx 210 Kcal/1 day

3210 - 210 = 3000

So, the individual should reduce caloric intake from 3210 per day to 3000 per day.

That's the "book" answer. The "real" answer should factor in activity level, the acquisition of muscle, and the loss of water.