A binary A-B alloy has \( \alpha \) and \( \beta \) phases at equilibrium. The ratio of weight percentages (wt.%) of \( \alpha \) to \( \beta \) is 4. The wt.% of A in \( \alpha \) and \( \beta \) phases is 70 and 20, respectively. The wt.% of B in the alloy is \(\underline{\hspace{2cm}}\) (round off to nearest integer).