Answer:
Step-by-step explanation:
21 feet below is written as -21
9 feet up is written as +9
So we have -21 + 9 = -12 or 12 feet below sea level
There isn’t a picture what do you need help with
11:12 is the answer to your question
(8.4*10^8) + (4.2*10^7)
= 882,000,000
= 8.82*10^8
Hope it helped :)
