In this task, you need to count the number of times the given letter appears in the given sentence.

Sentence: 'two pepperoni pizzas and a cup on a counter'. Find frequency of the letter 'u'
2

Sentence: 'a woman holds some baked goods at the convention'. Find frequency of the letter 'd'
3

Sentence: 'an adult and two children cross country ski through the snow'. Find frequency of the letter 'y'

1