Answer:
28.25 square units
Step-by-step explanation:
A circumference of the circle is

where r is the radius of the circle.
So,

The area of the circle is

Substitute the value of the radius:
Let's say that x represents hours that Elizabeth volunteers over 1 week. Katie volunteers x+3 and Siobhan x-1 hours per week. The equation that arises from condition in text is:
3*(x+3) = 3*(x + x-1)
x+3 = 2*x - 1
2*x - x= 3+1
x=4.
Elizabeth volunteers 7 hours
Katie volunteers 4 hours
Siobhan volunteers 3 hours