Here are the completed sentences in reported speech:

21. Chloe said, “I can’t understand these science books.”
Chloe said that she couldn’t understand those science books.

22. She said, “I am ironing my dress.”
She said that she was ironing her dress.

23. She said, “My brother is listening to the music.”
She said that her brother was listening to the music.

24. “I have been to Madagascar,” said Emma.
Emma said that she had been to Madagascar.

25. Jane said to me, “I’m coming.”
Jane said to me that she was coming.

26. Dad said to Mum, “I have paid the bill.”
Dad said to Mum that he had paid the bill.

27. She said, “My parents are here.”
She said that her parents were there.

28. She said, “My teacher is going to be off tomorrow.”
She said that her teacher was going to be off the next day.

29. He said, “We’ll go and get some fish and chips.”
He said that they would go and get some fish and chips.

30. William said, “Wake up at six every morning.”
William said that we should wake up at six every morning.