could you explain how the 2R/4R works im confused on that and how to do the rest

b. (i) Designate the configuration of the structures shown in Figure 1 according to the R.S-system. [Br (Z=35); CI (Z=17); F (2=9): 0 (Z=8); C (2-6); H (Z=1)] CH.CH tFET CH.CH Figure 1 (8 marks) (ii) Draw the perspective formula of each of the following compounds: (S)-3-chlorohexane (2,4R)-2-fluoro-4-methylhexane