1.) What are the four arithmetic means between 21 and - 24?

2.) Find the 15th term of the arithmetic sequence if the first term is -8 and the common difference is 5.

3.) If the second term of an arithmetic sequence is 17 and the fourth is 37, what is the third term?

4.) A stack of telephone poles has 30 poles in the bottom row. There are 29 poles in the second row, 28 in the next row and so on. How many poles are there in the 26th row?