Answer/step-by-step explanation:
The 300/40 comes from the fact that ¾ of a 400 meter swim is 300 meters, and if you want to know how long he took to do that, you need to divide by the speed, 40 meters per minute (meters divided by meters per minute = minutes). Likewise with the 100/35—that’s the last 100 meters he swam, at the slightly slower speed.
Just to bring it all the way home, average speed is total distance divided by total time. that the total distance is 400 meters. You know the total time is 300/40 + 100/35. Average speed, then, is:
Average Speed:
Round: 39 meters per minute
I think if wrong I'm sorry