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 how many hours each person volunteers each week (the graph says "volunteer hours per week" and "volunteer hours over 3 weeks")

Let x be the number of hours that Elizabeth volunteered in the hospital per week. With this representation, Katie volunteered for x + 3 hours per week and Siobhan volunteered for x - 1 hours per week. In three weeks, the equation would be,
                            3 (x + 3) = 3x + 3 (x - 1)
The value of x from the equation is,
                                 x = 4
Therefore, Elizabeth volunteered for 4 hours per week, Katie for 7 hours a week and Siobhan for 3 hours a week. Multiplying all these values by 3 would give the amount of time they spent in hospital for 3 weeks.