Two circles have areas of 16(pi) and 25(pi). find the ratio of their circumferences.

Area of the first circle = 16(pi)
We know that
Area of a circle = (pi) * (Radius)^2
Then
16(pi) = (pi) * (radius) ^2
(4)^2 = (Radius)^2
Radius = 4
Diameter = 8
Circumference = (pi) * Diameter
                         = 8(pi)
In case of the second circle
Area = (pi) * (Radius) ^2
25(pi) = (pi) * (Radius)^2
(5)^2 = (Radius)^2
Radius = 5
Diameter = 10
Circumference = 10(pi)
So
Circumference of first circle:Circumference of second circle = 8(pi):10(pi)
                                                                                               = 4:5