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

Sentence: 'a teenager witting on a futon couch holding gaming controls in both hands'. Find frequency of the letter 'c'
3

Sentence: 'a small boy in a high chair eating a cupcake'. Find frequency of the letter 'i'
4

Sentence: 'a bed with white sheets and pillow, and a box of tissue on the headboard'. Find frequency of the letter 'a'

6