$4)$ For a Code Division Multiple Access $($CDMA$)$ system, where each user transmits data spread over $4$ chips, and each user utilizes a code sequence consisting of $1\text{'}$s and $-1\text{'}$s$,$ show how a receiver can decode the signals for two users $(\backslash (\backslash$mathrm$\{$U$\}\_\{1\}\backslash )$ and $\backslash (\backslash$mathrm$\{$U$\}\_\{2\}\backslash ))$ using their respective spreading codes. $(10\backslash \%)$