TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a person is holding a chocolate doughnut with rainbow sprinkles'. Find frequency of the letter 's'

SOLUTION: 4

PROBLEM: Sentence: 'a passenger train that is going over a bridge'. Find frequency of the letter 't'

SOLUTION: 3

PROBLEM: Sentence: 'a person on a surfboard in the water'. Find frequency of the letter 'a'

SOLUTION:
4