Answer
(a) $V(t)=4000-900t$
(b) See the image below
(c)The slope -900 represents rate of change at which the price decreases with respect to $t$.
$V$-intercept represents initial price at $t=0$.
(d) $\$1300$
Work Step by Step
(a) We have a linear function $V(t)$, where $V(0)=4000$ and $V(4)=200$. ($V(t)$ represents price for given $t$ years).
In $4$ years the change is $3600$, it means $900$ change per year. Rate of change of $V(t)$ with respect to $t$ is $900$. So we can write the equation:
$V(t)=4000-900t$
(b) We can simply input values in the equation above and sketch a line. But note, keep $t$'s value positive(Since years cannot be negative) and to avoid any error keep in interval $[0, 4]$ (Because at some point $t$ price will get negative, which is not appropriate).
Graping calculator is also applicable.
See the image above.
(c) The slope -900 represents rate of change at which the price decreases with respect to $t$.
$V$-intercept represents initial price at $t=0$.
(d) $V(3)=4000-900\times3=4000-2700=1300$
$V(3)=\$1300$
