Katie, Elizabeth, and Siobhan volunteer at the
 hospital. In a week, Katie volunteers 3 hours
 more than Elizabeth does and Siobhan
 volunteers 1 hour less than Elizabeth. Over
 3 weeks, the number of hours Katie
 volunteers is equal to the sum of Elizabeth’s
 and Siobhan’s volunteer hours in 3 weeks.
 Complete the table to find out how many
 hours each person volunteers each week.