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

Sentence: 'a blue tripocal bird is perched on a wooden fence'. Find frequency of the letter 'd'
3

Sentence: 'there is an old stove with old pots on the burners'. Find frequency of the letter 't'
5

Sentence: 'a man on a court with a tennis racket'. Find frequency of the letter 'k'

1