Find the perimeter of a rectangle, one side of which is 280 mm and the other 6 times larger.

Let’s find the width of the rectangle from the condition: b = a * 6 = 280 * 6 = 1 680 mm.
As you know, the perimeter of a rectangle is calculated by the formula: P = (a + b) * 2, where a is the length of the rectangle, b is the width of the rectangle.
Substitute all known values into the formula: P = (280 + 1 680) * 2 = 560 + 3 360 = 3 920 mm.
Answer: The perimeter of the rectangle is 3,920 mm.