Question

A small submarine starts at - 1.260 feet in relation to sea level. Then it descends 5 feet per minute for 12 minutes What expression represents the new position of the submarine in relation to sea level?

Answer 1

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

Explanation: