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 a
fter 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.
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).
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.
To Decrease an amount in a given Ratio, we need to multiply by a fraction that is less than one. For example, in scaling down a recipe for four people into a recipe for 3 people, we would use the ratio of 3 : 4 which means we would multiply all our recipe amounts.