Just looking for someone to get me started, as I am absolutely lost on these problems:

The purchase of a "collector's item" is often made in hopes the item will increase in value. In 1998, Mark purchases a 1909-S VDB Lincoln Cent(in fair condition) for $150. By the year 2004, its value has grown to $190.

a) Use the relation(time since purchase,penny's value C) with t = 0 corresponding to 1998 to find a linear equation modleing the value of the coin

b) How much will the penny be worth in 2009?

c) How many years after the purchase will the penny's value exceed $250?

d) If the penny is now worth $170, how many years has Mark owned the penny?

Any help would be appreciated!