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

Sentence: 'a girl that has a kite in the air'. Find frequency of the letter 'r'
2

Sentence: 'two young ladies that are dancing in the room together'. Find frequency of the letter 'a'
4

Sentence: 'a woman uses a cell phone on the floor near a laptop'. Find frequency of the letter 's'

2