Final answer:
By adding the initial depth of 35.8 feet to the additional descent of 23.4 feet, the scientist is now 59.2 feet below sea level.
Step-by-step explanation:
The question asks to find out how many feet the scientist in a submarine is below sea level after descending further underwater. Initially, the scientist was 35.8 feet below sea level. After going down an additional 23.4 feet, we simply need to add the two depths to find the total depth below sea level.
Starting depth below sea level: 35.8 feet
Additional descent: 23.4 feet
To find the new depth below sea level, we add the two values together:
35.8 feet + 23.4 feet = 59.2 feet
So, after descending an additional 23.4 feet, the scientist is now 59.2 feet below sea level.