Решение этих задач https://gist.github.com/zaikays/6e09b966479c7975f28c#file-gistfile1-txt

soloving.py

#Решение задание №1:
original = "I like this World "
reverse = original[::-1]
print(reverse)

Решение задание №2:
original = "123123abc 2311 a c"
reverse = original[2::3]
print(reverse)

Решение задание №3:
count_this = 'aeiou'
original = "Python hAs an amazing fEature".lower() # Python 2 — .lowercase()
conted = sum(original.count(char) for char in count_this)
print(conted)