What is the value of the expression with base 3 and exponent 6

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.

1) you deposit $2,500 in an account that earns 4% simple interest. how much do you earn in eight years?

How is this equation completed? i cannot find any examples in the book.