Complex sentence: In "Beezus and Ramona", she is 9 years old and turns 10 at the end of "Beezus and Ramona" She remains this age in "Ramona the Pest".
Split into simpler sentences: In "Beezus and Ramona", she is 9 years old. She also turns 10 at the end of "Beezus and Ramona" and is this age in "Ramona the Pest".