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

Q: Sentence: 'a toasted sub sandwich is next to a salad'. Find frequency of the letter 'a'

A: 6
****
Q: Sentence: 'a big bear walks through some grass'. Find frequency of the letter 'a'

A: 4
****
Q: Sentence: 'many donuts are sitting on a wooden counter'. Find frequency of the letter 'n'

A:
6
****