Let RS be y.
Given T is the midpoint of RS that is RT = TS =

And W is the midpoint of RT,
that is RW = WT =

Given Z is the mid point of WS.
That is WZ = ZS =

Now TZ = TS-ZS =

But TZ is given as x.
That is

y=8x =RS.
A)length of RW =

B) length of WZ =

C) length of RS = y =8x
D) length of ZS= WZ = 3x.
Image is attached for explanation.