Priya's circle:
circumference = pi x Diameter
12.56 = pi x D
Solve for D:
12.56/ pi = D
Diameter = 4 cm
Since Clare's circle has a diameter that is 3 times the diameter of Priya's:
Clare's diameter = 4 x 3 = 12
Clare's circumference = 12 x pi = 37.7 cm