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

Sentence: 'a snow filled mountain with a guy with ski's'. Find frequency of the letter 'f'
1

Sentence: 'a number of small boats on a beach near an umbrella'. Find frequency of the letter 's'
2

Sentence: 'a view of a bridge from the bottom of it'. Find frequency of the letter 'o'

5