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

Sentence: 'a half eaten doughnut in a persons hand'. Find frequency of the letter 'h'
3

Sentence: 'a stuffed animal sitting on an empty bed'. Find frequency of the letter 'u'
1

Sentence: 'the baseball player is wearing a bright gold helmet'. Find frequency of the letter 'l'

5