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

Sentence: 'baseball player reaching back as he's about to throw the ball'. Find frequency of the letter 'e'
5

Sentence: 'an area that has surrounded by a metal fence'. Find frequency of the letter 'o'
1

Sentence: 'an old and beat up banana hangs out'. Find frequency of the letter 'p'

1