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

Sentence: 'some people sitting on surfboards in the water'. Find frequency of the letter 't'
4

Sentence: 'a group of people standing around a table filled with assorted electronic devices'. Find frequency of the letter 'w'
1

Sentence: 'blue and green bus coming out from under a building'. Find frequency of the letter 'r'

3