Final answer:
To find the car's rate in miles per hour, the formula to use is r = 180 miles / t hours, where r is the rate and t is the time in hours.
Step-by-step explanation:
We need to write an equation to find the rate at which the car was traveling in miles per hour, given that the car traveled 180 miles in t hours at a constant rate. The rate, often denoted as r, is found by dividing the total distance by the total time it takes to cover that distance.
The equation for rate is:
r = distance / time
In this case, the car traveled 180 miles and the time taken is t hours. So the equation becomes:
r = 180 miles / t hours
r = 180 / t
This equation can be used to calculate the average speed, or rate, at which the car was traveling.