The length of the rectangle is 3 cm and the width is 2 times greater. Find the perimeter and area of the rectangle.

1) Since the length of the rectangle is 3 cm, and the width is 2 times the length, in order to find the value of the width of the rectangle, you need to multiply the value of the length by two: 3 cm * 2 = 6 cm width of the rectangle.
2) The perimeter of a rectangle is equal to the sum of all its sides. Since the opposite sides of the rectangle are equal, then P = 2 * a + 2 * b. Substituting the values of the lengths of the sides, we get: P = 2 * 3 cm + 2 * 6 cm = 6 cm + 12 cm = 18 cm.
3) The area of the rectangle is equal to the product of length and width: S = a * b, S = 3 cm * 6 cm = 18 sq cm.