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: 'two giraffes, one standing and one laying down'. Find frequency of the letter 'g'
3

Sentence: 'group of vehicles traveling down a busy city street'. Find frequency of the letter 'g'

2