Answer
Please see the work below.
Work Step by Step
We know that Chlorine forms the $ClO_3^{-}$ ion. Hence bromine should form $BrO_3^{-}$ ion and potassium forms $K^{+}$ ion, that's why Lithium should be $Li^{+}$. So, the formula for lithium bromate is given as $LiBrO_3$.
