A. Y= -7.50x+585(not entirely positive on this one ,but we are learning this in school right now for me)
B. y=-7.50(15)+585
C. solve the equation up above so multiply -7.50 by 15 (weeks) which would give you -112.50 then add 585 which gives you 472.50 which should be your answer
so there is 472.50 dollars left in account after one year.
hope this helped!