Question

Oliver is going to drive from his house to City A without stopping. Oliver plans to drive at a speed of 40 miles per hour, and after driving for 3 hours, he will be 80 miles away from City A. Write an equation for the function

D
(
t
)
,
D(t), representing Oliver's distance from City A
t
t hours after leaving his house.

Answer 1

D(t) = 200 - 40t

Explanation:

Oliver lives some distance m away from city A. We know as he drives, he will get closer to city A, so his distance should decrease. so we are expecting a negative coefficient for t, let's call it r.

so we have D(t) = m - rt

we know he is driving at 40 mph, so r=40

D(t) = m - 40t

we know that after driving for 3 hours, he is 80 miles from city A.

D(3) = 80 = m - 40*3

80 = m - 120

200 = m

and so we have our equation!

D(t) = 200 - 40t

Answer 2

D(t)=200-40*t

Explanation:

He was already travelling for 3 hours, so he travelled 3*40=120miles. Total distance between his house and city A is 120+80=200miles. And he is travelling 40m/h. So I think this function represent his distance from city A depending how much time he was travelling (t).

D(t)=200-40*t