You must mean the depth of the submarine.
to make sum = zero the depth of the sub must be -1600 ft..
In order of problems/numbers - 4, 3, 5, 6, 1, 2
Word Problem:
Take a number, <em>x</em>, double it and then take that result away from 10.
Expression:
The given inequality is:

This inequality can be divided in two parts as:
a)

b)

Solving part a:

Solving part b:

Therefore, the solution to the given inequality is

and

. Combining both the ranges we get the solution:

.
In interval notation, this solution can be expressed as [1,5]