instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a microwave oven with a yellow note on the door'. Find frequency of the letter 'w'
answer:
3


question:
Sentence: 'a gray airplane with metal petals on the wings takes off from an airport'. Find frequency of the letter 'i'
answer:
4


question:
Sentence: 'a teenage boy performs a skateboard stall on a half pipe'. Find frequency of the letter 'r'
answer:

3