First things we do is to find the Circumference of a circle using the formula

C = 2π(d/2) where, C is the circumference and d = diameter of the circle

we will use π=22/7 and d = 42 cm

C = 2(22/7)(42/2)

C = 2(22/7)(21)

C = (2)(22)(3)

C = 132

There are 60% of the circumference of a circle that is cut to form a rectangle.

We will get that 60% by multiplying it to the circumference to get the Perimeter of the rectangle.

P = (0.60)(132)

P = 79.2

Perimeter of the rectangle is

P = 2L + 2W, where P is the perimeter, L is the length, and W is the width

Since, length is 3 times its width, we will denote this as

L = 3W

So we have

P = 2L + 2W

79.2 = 2(3W) + 2W

79.2 = 6W + 2W

79.2 = 8W

79.2 / 8 = 8W / 8

9.9 = W

W = 9.9 cm

Therefore, the width of the rectangle is 9.9 cm.