Isaac currently has $200 in his savings account. He plans to deposit $20 each week. 
 Which function represents the total amount of money he has saved. (S). as a function of the number of weeks, (W), since he had $200 in the account? 
 A. S (W) = 200+20w
 B. S (w) =200w+20w 
 C. S (w) = 200-20w 
 D. S (w) = 20(w+ 200)