The length of the rectangle is 21cm and the width is four-sevenths of the length. Find its perimeter.

Let’s find the value of the width of the rectangle specified to us, for this we need to multiply the value of the length of the rectangle specified by us by the specified fraction of the width in the length:

21 * 4/7 = 12 cm – this is the value of the width of the rectangle indicated to us;

We will find the value of the perimeter of the rectangle specified to us, for this we need the value of the length of the rectangle specified to us, add the value of the width of the rectangle given to us, and multiply the result by two:

(21 + 12) * 2 = 66 cm – this is the value of the perimeter of the rectangle indicated to us.

Answer: 66 cm – this is the value of the perimeter of the rectangle indicated to us.