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

Sentence: 'a dog laying on the back of a boat in the water'. Find frequency of the letter 't'
4

Sentence: 'a cat sleeping near lots of pairs of shoes'. Find frequency of the letter 'r'
2

Sentence: 'a woman dressed as tooth fairy holding a wand'. Find frequency of the letter 'o'
4