The length and width of the rectangle together are 21 cm. What is the length and width if the length is 6 times its length?

1) Let x be the width of the rectangle in centimeters, then the length is x * 6 centimeters. We know that the length and width of the rectangle together are 21 centimeters. Let’s make the equation:
x + x * 6 = 21;
x * (1 + 6) = 21;
x * 7 = 21;
x = 21: 7;
x = 3 centimeters – the width of the rectangle;
2) 3 * 6 = 18 centimeters – the length of the rectangle.
Answer: 3 and 18 centimeters.