In this task, you need to count the number of times the given letter appears in the given sentence.

Sentence: 'a man flying through the air on a bicycle'. Find frequency of the letter 'u'
1

Sentence: 'man riding a skate board down the little board way'. Find frequency of the letter 'k'
1

Sentence: 'a woman with long nails charging an ipod'. Find frequency of the letter 'a'

5