The melting points of metal A and metal $B$ are $1000C$ and $750C$ respectively. A number of alloys are prepared by mixing different proportions of A and B$,$ and the arrest points of cooling curve of each alloy are given in the following table.

$\backslash$table$[[$B in A$,$ wt$.\%,5,10,20,30,40,50,60,70,80,90$