Answer:
180/t = r
Step-by-step explanation:
In this question, we would have to write an equation that represents the scenario given.
We know that the car traveled 180 miles at a constant rate.
We would use the y = mx + b format for the equation, but replacing the variables with "r" and "t"
We know that 180 will be our y-variable, since that would be the base of the equation:
180 = ???
And to find how long/fast it will take the car, we would need to multiply the rate of speed "r" and time "t" in order to get our distance.
Plug it into the equation:
180 = rt
With this set up, you can find the rate of speed of the car when you know the time.
You would simply solve it as:
180/t = r
. Then 
, and so as 
, you have 
. The limit is then equivalent to