Step1. Total valence electron

BH4- = 3e- + 4(1e-) + 1e- = 8e-

step2. Lewis structure

formal charge :

\(\begin{array}{|l|l|}\hline C&H&O(\text{single bond})&O(\text{double bond})\\\hline4-4=0&1-1=0&6-7=-1&6-6=0\\\hline\end{array}
\) step1. total valence electron

As Cl4- = 5e- + 4(7e-) +1e- = 34e-

step 2. lewis structure

\(\begin{array}{|l|l|}\hline As&Cl\\\hline5-6=-1&7-7=0\\\hline\end{array}\)