How many strings of eight english letters are there
a.That contain no vowels, if letters can be repeated?
b.That contain no vowels, if letters cannot be repeated?
c.That start with a vowel, if letters can be repeated?
d.That start with a vowel, if letters cannot be repeated?
e.That contain at least one vowel, if letters can be repeated? F ) that contain exactly one vowel, if letters can be repeated? G) that start with x and contain at least one vowel, if letters can be repeated? H) that start and end with x and contain at least one vowel, if letters can be repeated?