TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a tennis player that is running to get the tennis ball'. Find frequency of the letter 't'

SOLUTION: 7

PROBLEM: Sentence: 'pedestrian in stripe clothing standing on street corner'. Find frequency of the letter 's'

SOLUTION: 4

PROBLEM: Sentence: 'a couple of people walking down a sidewalk next to parked cars'. Find frequency of the letter 't'

SOLUTION:
2