A small submarine starts at - 1,260 feet in relation to sea level. Then it descends 5 feet per minute for 12 minutes. What is the new position of the submarine in relation to sea level? - 1,260 + (-5) (12) = - 1,260 + 60 = - 1,200

That would be - 1260 + 12 (-5) = - 1260 - 60 = - 1320 feet

The submarine is at - 1260 ft.

It descends 5 ft/min for 12 min.

12 min * 5 ft/min = 60 ft.

It descended 60 ft, so you must subtract 60 ft from - 1260 ft.

-1260 ft + (-5) (12) ft = - 1260 ft - 60 ft = - 1320 ft

The error in the last line in the problem is that (-5) (12) = - 60, not 60.

The correct line is:

-1260 + (-5) (12) = - 1260 - 60 = - 1320