The speed at which Mario can walk is given in the question and it is 3.9 miles/hour. Also we get to know from the question that Mario walked for 0.72 hours. The question requires the answer to the distance for which Mario walked.
Now
Mario in 1 hour can cover a distance of 3.9 miles
The n
The distance covered by Mario in 0.72 hours = (3.9 * 0.72) miles
= 2.808 miles
Then the distance covered by mario in o.72 hours is 2.808 miles.