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

Sentence: 'a train on a train track going through a bunch of trees'. Find frequency of the letter 'u'
2

Sentence: 'a lady is standing near a luggage stand at the air port'. Find frequency of the letter 'a'
9

Sentence: 'cars are parked in the parking spaces with meters'. Find frequency of the letter 'p'

3