You are given two points in the linear function. At time 0 years, the value is $3000. At time 4 years, the value is $250. This means you have points (0, 3000) and (4, 250). You need to find the equation of the line that passes through those two points.
y = mx + b
m = (y2 - y1)/(x2 - x1) = (3000 - 250)/(0 - 4) = 2750/(-4) = -687.5
Use point (0, 3000).
3000 = -687.5(0) + b
b = 3000
The equation is
y = -687.5x + 3000
Since we are using points (t, v) instead of (x, y), we have:
v = -687.5t + 3000
Answer: d. v = -687.50 t + 3,000
