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

Sentence: 'a woman at a table checking her cell phone'. Find frequency of the letter 'a'
5

Sentence: 'a plastic plastic plate topped with three different type of food'. Find frequency of the letter 'l'
3

Sentence: 'a man uses a knife to chop up some carrots'. Find frequency of the letter 'k'

1