Calculate the average between 200 and 4100

What is the answer to this question? i'm a bit stumped. also how do i do it? 5(x - 4) = 2(x + 5)

If the ratio of sum of the first m and n terms of an ap is m2 : n2 , show that the ratio of its mth and nth terms is (2m − 1) : (2n − 1).

Jalen charges $25.50 for every 3 hours of yard work he does for his neighbors. ralph charges $34 for every 4 hours of work that he does. who charges less? opinions: 1.they charge the same amount 2.jalen 3.ralph