Answer: Approximately 23.55 units
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Step-by-step explanation:
For now, we'll just find the perimeter of the full circle. The term "circumference" is the same as the perimeter of the circle.
Use the circumference formula to get
C = 2*pi*r
C = 2*3.14*5
C = 31.4
The distance around the full circle is approximately 31.4 units. It's approximate because pi = 3.14 is approximate.
We don't want the full distance around the circle. Instead, we want just the length of the green arc shown in the drawing. This is exactly 3/4 of the full circle, aka 3/4 = 0.75 = 75% of the full perimeter.
The length of the green arc is about 0.75*C = 0.75*31.4 = 23.55 units long. Imagine using a cloth ruler (used in tailoring clothes) as one way to confirm that this arc length is roughly 23.55 units long. Or you could imagine unwrapping this curved portion to lay it completely straight and flat against a ruler.