You can set up an equation. Let x = measure of the length.
Width: 2/3x Length: x
From the question, we know that the perimeter is 70 and based on our prior knowledge, we know that for a rectangle, the perimeter is equal to 2 times the length added to two times the width.
2(2/3x + x) = 70 4/3x + 2x = 70 10/3x = 70 x = 21
So the length is 21 meters. And since the width is 2/3 the length, 2/3 x 21 is 14. So the width is 14 meters.
And if you add 21 + 21 + 14 + 14, it will equal 70 meters.
Now let's find the area. 21 x 14 = 294 square meters.
