Answer:
d(t) = -20t -260
Step-by-step explanation:
We are given two points ...
(t, d) = (3, -320) and (8, -420)
The 2-point form of the equation of a line can be useful when 2 points are given.
y = (y2 -y1)/(x2 -x1)(x -x1) +y1
Substituting the given points, we have ...
d(t) = (-420 -(-320))/(8 -3)(t -3) -320
d(t) = -20(t -3) -320
d(t) = -20t -260