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

Sentence: 'a large bathroom with marble floor, counter, and bath'. Find frequency of the letter 'f'
1

Sentence: 'a player swings his bat at a baseball game'. Find frequency of the letter 'p'
1

Sentence: 'a suitcase bag packed with roller skates hanging from the top and back of it'. Find frequency of the letter 'r'

3