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

[EX Q]: Sentence: 'a bus with two floors belonging to london country'. Find frequency of the letter 't'
[EX A]: 4

[EX Q]: Sentence: 'a person is riding in a cart pulled by a horse'. Find frequency of the letter 'a'
[EX A]: 4

[EX Q]: Sentence: 'several benches stand by the side of a river'. Find frequency of the letter 'a'
[EX A]:
3