In this task, you need to count the number of words in a sentence that start with the given letter. Answer with numbers and not words.

Sentence: 'a woman sitting on some stairs by a ball and backpack'. How many words start with the letter 'b' in the sentence.
3

Sentence: 'montage color photograph of helmeted motorcycle riders and a rural fire station'. How many words start with the letter 'r' in the sentence.
2

Sentence: 'a small airplane sitting on top of a runway'. How many words start with the letter 'a' in the sentence.

3