For example the absolute value of -5 is 5
Hope this helped :)
part 1 answer = 8
part 2 answer = 72
part 1 explanation = add all of the numbers, then divide by how many numbers you have. so, 200/25 = 8.
part 2 explanation = not gonna lie, this is hard to explain, so just google how to do it.
goog may have it for you