Tomas works as an underwater photographer. he starts at a position that is 19 feet below sea level. he rises 9 feet, then descends 16 feet to take a photo of a coral reef. enter an expression to find his position relative to sea level when he took the photo and then evaluate the expression.

Expression:

X = Xo + 9 feet  - 16 feet
X = - 19 feet + 9 feet - 16 feet
X = - 26 feet (26 feet below the sea level)

Explanation:

1) Call Xo the initial position, and X the variable to indicate the actual position

2) Use position 0 for sea level

3) use negative sign for positions under the sea level

4) use positive sign for positions above the sea level

5) Expression:

Final position = initial position + movements upward - movements downward

X = Xo + 9 feet - 16 feet

X = - 19 + 9 feet - 16 feet = - 26 feet