Spending Question and functions.

Hello everyone, I've been trying to solve this question for quite some time but I cannot do it. If anyone can show me how it would be greatly appreciated.

The cost of a refrigerator is $700. It takes $100 of electricity to keep it running for a year and the appliance will last 15 years.

a)Determine the total annual cost of the refridgerator. Include the price of electricity and remember that you have it for 15 Years.

My question about a, if its asking for annual cost (yearly) why does it tell it to remember we have it for 15 years?

b) Determine a function that shows the annual cost of the fridge,

c) Determine the asymptotes in this function? What do they mean in a question like this?

My answer to c: The asymptotes would have to be x=0 and x=15 because you get the fridge at 0 and it lasts 15 years.

d) If another brand of refrigerator costs $2000 but lasts 20 years, is it worth it to buy that?