Answer:15
Step-by-step explanation:
You can see that AC and DF are the simular so you would set up the equation
9/x multiplied by 15/25 and through cross multipying which is 9 times 25 and x times 15 you would get 225 = 15x then divide both sides by 15 and the answer is 15 which hopefully is the right answer for line DF
