The width of the rectangle is 3cm. What is the length if the perimeter is 16cm?

1. Let the length of the rectangle be x cm.

2. The perimeter of a rectangle is equal to the sum of the lengths of all its sides, which means that the perimeter of this rectangle is:

x + 3 + x + 3 = 2 * (x + 3);

3. By the condition of the problem, it is known that the perimeter of the rectangle is 16 cm. Then we write down and solve the equality:

2 * (x + 3) = 16;

x + 3 = 16/2 = 8;

x = 8 – 3 = 5;

4. We got that the length of the rectangle is 5 cm.

Answer: the length of the rectangle is 5 cm.