This seems a little bit like homework, so I will just get you started and you can ask more questions and check your estimate for part a), with us.

Given body weight is the dependent variable and age is in single years:

B.) A single year increase in age for a person who doesn't workout results in an estimated 8% increase in odds of bodyweight = 1. This is also given you don't need to include the intercept in the formula, which I don't recall being necessary.

Now you need to incorporate the other variable as well to get a).