input: Write a python function to calculate the sum and average of a list of numbers.
  assert calculate_sum_and_average([10, 15, 20, 25]) == (70, 17.5)
  assert calculate_sum_and_average([1, 2, 3, 4, 5]) == (15, 3.0)
  assert calculate_sum_and_average([7, 14, 21, 28]) == (70, 17.5)
output: def calculate_sum_and_average(numbers):
      total = sum(numbers)
      average = total / len(numbers)
      return total, average