Maria and John's Running Distances Ratio

Maria and John are preparing for a marathon and are tracking their running distances. Maria runs at a speed of 6 miles per hour, while John runs at a speed of 9 miles per hour. They both start running at the same time and run for the same amount of time.

What is the ratio of the distance Maria runs to the distance John runs after they have both run for the same duration?

Express your answer as a fraction in simplest form.