For this you are going to want to put it into an equation. You can have L=length and W=width. The equation for perimeter is Perimeter = L + L + W + W because there are two ends to the court and two sides. In this problem length (L) is 6 meters longer than twice the width (W). This can be translated to:
L = 2W + 6 meters
The next step would be to substitute L in the perimeter equation with what we just did above.
Perimeter = (2W + 6) + (2W + 6) + W + W
You could simplify this by combining like terms:
Perimeter = 2(2W + 6) + 2W
We would then substitute in the information that was given in the problem, that perimeter is 84 feet.
84 = 2(2W + 6) + 2W
And now we would want to distribute the 2 outside the parentheses onto what is inside:
84 = 4W + 12 + 2W
We can now combine the terms with W attached to them.
84 = 6W + 12
Now subtract the 12 from each side.
72 = 6W
Now, to get the W by itself, you would divide the 6W by 6 and the 72 by 6.
12 = W
We just found that the width is 12 meters. Now plug this information into the formula that we found for the length (L) earlier.
L = 2W + 6
L = 2(12) + 6
L = 24 + 6
L = 30
The length is equal to 30 meters.
To check the answers you can put them back into the original perimeter equation.
Perimeter = L + L + W + W
84 = 30 + 30 + 12 + 12
84 = 60 + 24
84 = 84