The two rectangles have the same perimeter. The length of the first is 12 cm, and the width is 3 times less.

The two rectangles have the same perimeter. The length of the first is 12 cm, and the width is 3 times less. Find the length of the second one if the width is 6 cm.

1 rectangle:
Length = 12 cm, width 3 times less than length.
2 rectangle:
Length -? cm, width 6 cm.
The perimeters are equal.
1) 12/3 = 4 (cm) – width of 1 rectangle
2) 12 + 12 + 4 + 4 = 32 (cm) – perimeter
3) 32-6-6 = 20 (cm) – 2 lengths
4) 20/2 = 10 (cm) – length of 2 rectangles
Answer: 10 cm