Trouble Setting Up Equation for Weight Loss Over Time

[ilikeintegrals]

I am trying to set up an equation to find weight loss over time where the amount of exercise and number of calories consumed is constant. I am having trouble with it. The base amount of calories that your body burns every day (BMR) is based on your current weight. BMR is the base metabolic rate and is given by:
BMR = 10*weight + 6.25*height -5*age + 5

Weight loss (∆W) is given by:
Initial weight - ((BMR + Exercise - Food intake)*∆days)/7700
W_i - ((BMR+E-C)×∆d)/7700

7700 is the calories in 1kg (just in case you were wondering). I am to assume that the calorie intake, the height and amount of exercise is constant. The age (in years) from BRM will be related to the days from the ∆W equation.
Help is appreciated.

 

[Bystander]

I am having trouble with it.

What kind of trouble; you've listed all the information you wish to include, and relationships among the variables. Where's the sticking point? What information did you want to pull out?