What if you know that "140 km traveled in 6 hours, 1 hour costs $17. How much does 1 km cost?". Thus, you need to find the price per 1 kilometer. In my humble opinion, you can solve this task in two steps - multiplication and division. Multiply the hour price by the total number of hours and divide the result by the total number of kilometers traveled.
But, our website is made to automate the calculations. Now you need to enter the values of three variables, and you will automatically receive an answer. Thus, talking about automation - we are freeing the user from pressing the "multiply", "divide", and "equals" buttons, and, potentially, from brain activity if he/she suddenly decides to solve this problem in mind.