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

Sentence: 'a man with a skateboard that is in the street'. Find frequency of the letter 'o'
1

Sentence: 'there is a zebra that is walking enar a car'. Find frequency of the letter 'r'
4

Sentence: 'some giraffes are standing around on an open day'. Find frequency of the letter 'd'

3