Diameter of the circular garden = 21 m

\Radius of the circular garden = 21/2 m

Now

Circumference of circular garden =2 πr

= 2 x 22/7 x 21/2

= 22 x 3 = 66 m

The gardener makes 2 rounds of fence so the total length of the rope of fencing

= 2 x2 πr = 2 x 66 = 132 m

Since the cost of 1 meter rope = Rs 4

Therefore, cost of 132 meter rope = 4 x 132 = Rs 528