The verbal construction in Japanese to ask how much something costs works slightly different than in English. Instead of combining the question word ‘how’ with the quantifier ‘much,’ Japanese has its own word, ‘いくら,’ with the same meaning.
In Japanese, it is preferable to omit the subject of the sentence whenever possible. When answering a question like, ‘what color is the sky’ (‘そらはなんいろですか’) in Japanese, we do not need to repeat the word ‘sky’ or substitute it for the pronoun ‘it’ because the topic of conversation has already been established; instead, we would literally say ‘is blue’ (‘あおいです’). Many English speakers learning Japanese will include the subject even when it is not necessary—try to avoid this as you practice Japanese. If something isn’t clear, you can always specify or ask a follow-up question.
In this problem, we don’t know what the question is, but we know the answer translates to ‘it is 24,000 yen.’ We can see that the only item in the provided pictures that costs that much is the bicycle. Using the ‘XはYです’ construction we learned in Chapter 1, we can provide the question as the following:
じてんしゃはいくらですか。
jitensha ha (wa) ikura desu ka.

In this problem, we don’t know what the question is, but we know the answer translates to ‘it is 24,000 yen.’ We can see that the only item in the provided pictures that costs that much is the bicycle. Using the ‘XはYです’ construction we learned in Chapter 1, we can provide the question as the following:
じてんしゃはいくらですか。
jitensha ha (wa) ikura desu ka.