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

Sentence: 'a man paddle boarding by a boat dock in a city'. Find frequency of the letter 'o'
3

Sentence: 'a teddy bear is sitting on a heart shaped patio chair outside'. Find frequency of the letter 'i'
6

Sentence: 'a green display of green and yellow cupcakes'. Find frequency of the letter 'p'

2