If x:y=4:9 and y:z=3:8, then the duplicate ratio of x:z is ____
If x:y=2:3 and y:z=2:3, then x:z=(a) 2:3(b) 3:4(c) 5:7(d) 4:9
If x:y=7:9 and y:z=15:7,find x:z