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

[Q]: Sentence: 'a dog has found a rather large stick for playing fetch'. Find frequency of the letter 't'
[A]: 3


[Q]: Sentence: 'a group of people walking down a rain soaked street with umbrellas'. Find frequency of the letter 'w'
[A]: 3


[Q]: Sentence: 'a stand with various items on it including thread on scissors'. Find frequency of the letter 'a'
[A]:
4