please help me i dont get it

Answer:
The last option would be your answer.
Step-by-step explanation:
Let x be the common multiplier of the ratio. Therefore, the length is 9x and the width is 8x. The formula for the perimeter of a rectangle is
2 * L + 2 * W = 68
2*L = 2* 9x = 9x + 9x
2*W = 2*8x = 8x + 8x
Since the perimeter is 68
9x + 9x + 8x + 8x = 68