Answer: D
Step-by-step explanation:
Think of it logically: A and C are not below sea level so you can cross them out. And B doesn't work because if you decrease -10 by 10 you get -20. So, D is correct.
Step-by-step explanation:
3x+7y-12=0
3x+7y=12
3x=12-7y
x=12-7y/3