You can use ratio and proportion in this problem.
Segment DC / Segment CB = Segment ZY / Segment YX
2.3m / 4.2m = k / 8.4m
K = 8.4 (2.3 / 4.2)
K = 23/5 or 4.6 m
Answer= 4.6 m
A.
rolling a 4, rolling a prime number
B.
rolling a 3, rolling a prime number
C.
rolling a 2, rolling an even number
D.
rolling a 5, rolling an odd number