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

Example Input: Sentence: 'food sitting in bowls on table with checked tablecloth'. Find frequency of the letter 't'
Example Output: 6

Example Input: Sentence: 'one woman is arranging the other woman's hair'. Find frequency of the letter 'o'
Example Output: 4

Example Input: Sentence: 'a house cat is taking a bite from a banana'. Find frequency of the letter 't'
Example Output:
3