Total of 8 times
Distance is 0.25 miles
8 * 0.25 is 2 so a total distance of 2 miles
We know his avg swim rate to be 60 minutes per mile, meaning if he traveled 2 miles then we multiply it by 60 to get our total time taken.
60min/mile * 2 miles = 120 minutes total
So, step D is the same as what I've done to calculate the total time it will take Tristan to swim around the lake