Circumference one = (2R)*pi let that value be 2x C second = 5x = (2R)*pi * 5 / 2 = (5R)*pi So Radius one / Radius two = 2 / 5 Area1:Area2=pi(2R)^2:pi(5R)^2=pi(4R^2):pi(25R^2), pi cancel out we get 4R^2:25R^2, now R^2 cancel out and we get ratio of 4:25
