The width, w, of a rectangle is equal to 3/7 of its length, l. the length, l, of the rectangle is 21 inches.

what is the perimeter of the rectangle?
what is the area of the rectangle, in square inches?

Because the width is 3/7 of 21, we can multiply 3/7 by 21 to find the width.  3/7 * 21 = 9.  So, the width is 9.

Now we know that the width is 9 and the length is 21.  From this, we can find the perimeter and area of the rectangle.  The perimeter is equal to 9 + 9 + 21 + 21 = 60.  So, the perimeter is 60 inches.

Now, we need to find the area.  We do this by multiplying 21 * 9.  This is equal to 189, so the area is 189 square inches.