a business buys a computer for $3,000. After 4 years the value of the computer is expected to be $250. The value, v, can be related to the time in years, t, in a linear equation. Which equation models the relationship between v an t?

a.v=250t
b.v=-250t
c.v=687.50t-3,000
d.v=-687.50t+3,000