I need help with this problem:
Polly the parakeet tweets all day long.  When she is happy, she tweets 18 times per minute.  When she is hungry, she tweets 4 times per minute.  And when she watches herself in the mirror, she tweets 45 times per minute.  During a time period where she is happy for 20 minutes, hungry for 20 minutes, and watches her reflection for 20 minutes, what is the total number of times she will tweet?