What is the length of AB? (Look at picture)

Select all the correct answers. what is 221,000,000,000,000,000,000 expressed in scientific notation?

What is the 12th term of b(n)=-4-2(n-1)

10 ! a train starts from grand city and travels toward belleville 388 miles away. at the same time, a train starts from belleville and runs at the rate of 47 miles per hour toward grand city. they pass each other 4 hours later. find the rate of the train from grand city.