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

Sentence: 'a baseball player dropping his bat and starting to run'. Find frequency of the letter 'o'
2

Sentence: 'an airplane is being towed away from the jet bridge'. Find frequency of the letter 's'
1

Sentence: 'a dog sitting in the back of a truck flat bed'. Find frequency of the letter 'h'

1