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

[EX Q]: Sentence: 'two zebras feed on a plant through some wire mesh'. Find frequency of the letter 'o'
[EX A]: 4

[EX Q]: Sentence: 'a black computer with a screen reading "press any key to begin."'. Find frequency of the letter 'a'
[EX A]: 5

[EX Q]: Sentence: 'members of the coalition forces play soccer with afghanis at the kabul airport'. Find frequency of the letter 'a'
[EX A]:
7