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

Sentence: 'two little girls playing with a bat and a tennis ball'. Find frequency of the letter 'w'
2

Sentence: 'a man holding a brown paper bag kite'. Find frequency of the letter 'b'
2

Sentence: 'a pile of stones sitting on the side of a road with some signs above it'. Find frequency of the letter 'd'

2