solution in the table below. What is the improvement index for the empty cell Source $1$ Destination $3?$

$\backslash$table$[[$OSTS$,$Dest $1,\frac{?}{\text{b}\text{a}\text{r}}($ Dest. $2),$Dest $3,\frac{?}{\text{b}\text{a}\text{r}}($ Dest. $4),$Supply$],[$Sourc$,,18,9,11,],[,19,1,30,,\frac{?}{\text{b}\text{a}\text{r}}(14)$