Answer:
b is the answer
Explanation:
after things are used don't they get replaced
Answer:
The entity relationship (ER) data model has existed for over 35 years. It is well suited to data modelling for use with databases because it is fairly abstract and is easy to discuss and explain. ER models are readily translated to relations. ER models, also called an ER schema, are represented by ER diagrams.
Answer:

Explanation:
The mass inside the rigid tank before the high pressure stream enters is:



The final mass inside the rigid tank is:



The supplied air mass is:


