Build a rectangle with a perimeter of 18 cm and, in addition, one side: 1) 2 times larger than the other

Build a rectangle with a perimeter of 18 cm and, in addition, one side: 1) 2 times larger than the other 2) shorter than the other by 4 cm.

Find the sides of a rectangle whose length is twice its width, denoting the width as x cm, making an equation for its perimeter.

(x + 2x) * 2 = 18;

6x = 18;

x = 18/6 = 3 cm.

3 * 2 = 6 cm.

Answer: sides 3 and 6 cm.

Similarly, we will compose an equation for the perimeter of a rectangle whose width is 4 cm shorter than its length.

(x + x + 4) * 2 = 18;

4x + 8 = 18;

4x = 10;

x = 10/4 = 2.5 cm;

2.5 + 4 = 6.5 cm.

Answer: sides 2.5 cm and 6.5 cm.