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

[Q]: Sentence: 'a few giraffes standing in a field looking around'. Find frequency of the letter 'e'
[A]: 3


[Q]: Sentence: 'two pepperoni pizzas and a cup on a counter'. Find frequency of the letter 'u'
[A]: 2


[Q]: Sentence: 'a system failure message over windows on a computer screen'. Find frequency of the letter 't'
[A]:
2