After 8 minutes, a vessel had descended 640 feet. What was the change in elevation of the
vessel each minute?

80

Step-by-step explanation:

It's super simple if after 8 minutes a vessel had descended 640 feet the change in the elevation of the vessel was 80ft each minute.  Hope this helps :)

80 feet per minute

Step-by-step explanation:

10 down (bang1)

5 up

5down (2)

2.5 up

2.5 down (3)

1.25 up

1.25 down (4)

now add them up : )

hoped i lol