Answer:
His position is now on -18 below sea level
Step-by-step explanation:
So since Tomas is 15 feet below sea level, that means that it's -15. He rose 9 feet which now he is -6 feet below sea level. Now he descends 12 feet which means he goes back down and now he is at -18 below sea level.
Start with the parentheses
Perimeter = 2(length + width)
p = 2(10'5" + 9'8")
p = 2(19'13")
p = 38'26"
26" = 2'4"
So...
38' + 2'4" = 40' 4" for the perim,eter