How old do cosmologists believe the universe is, and what are some of the methods they use to determine this?

Why is paper currency considered flat money ? a) it is backed up with gold and silver deposits b) it has value because people will accept it in exchange for a good or service c) it is easy to carry and transfer

Which factor contributed to the rise of african empires such as ghana and mali?

Sariah enters a room with several chirping crickets in it. upon first entering the room, sariah can hear the chirping; however, as she begins to talk to her friends, she is no longer aware of the chirping even though it is still there. the fact that sariah no longer perceives the chirping sound demonstrates sensory