instruction:
In this task, you need to count the number of times the given letter appears in the given sentence.
question:
Sentence: 'a girl laying on a bed posing for a picture'. Find frequency of the letter 'i'
answer:
4


question:
Sentence: 'man riding a skate board down the little board way'. Find frequency of the letter 'k'
answer:
1


question:
Sentence: 'end of a train just past a road crossing, pulling into a village station'. Find frequency of the letter 't'
answer:

6