TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'two boys are doing skateboard jumps in the street'. Find frequency of the letter 's'

SOLUTION: 4

PROBLEM: Sentence: 'a train sits on a railroad track as a metal awning covers it'. Find frequency of the letter 'l'

SOLUTION: 2

PROBLEM: Sentence: 'a snow boarder catches air between two snow mounds'. Find frequency of the letter 'b'

SOLUTION:
2