Simplify the following text for a Grade 10 native English-speaking person.
Original: 45 songs were written by vocalist and guitarist Billie Joe Armstrong by October 2007 , but the band members did not start studio work with the producer , Butch Vig until January 2008 .
Simplified: Forty-five songs were written by singer and guitarist Billie Joe Armstrong by October 2007 , but the band members did not enter studio work with Vig until January 2008 .