Python:

1.Write a function letter_count that takes a string argument and returns a dictionary of the number of times each letter occurs in the string, ignoring case.

2. Write a function both_strings that takes 2 string arguments and returns a set consisting of the letters that are contained in both strings, ignoring case.

3. Write a function repeats_num that takes a list of ints and returns True if the list contains a number that appears twice in a row.

4. Write a function order_summary that takes a list of order details as (item, price, quantity) tuples, and returns a (cost, number) pair representing the total cost of the order and the total number of items.