Answer:
[tex]f(t) = -400t+2070[/tex]
Step-by-step explanation:
According to the information of the problem the plane is traveling at a constant velocity therefore the function that models that gives the distance of the plane from city B at time t hours would be linear. Something like this.
[tex]f(t) = mt+b[/tex]
The velocity is the slope of the line and if you take B as your reference you would be going backwards therefore we would say that [tex]m = -400[/tex] . And as I mentioned before if you take B as your reference your starting point would be 2070 miles away, therefore the function would be
[tex]f(t) = -400t+2070[/tex]
