In the following reaction:

$\mathrm{A}+2\mathrm{B}+3\mathrm{C}\rightleftharpoons \mathrm{A}{\mathrm{B}}_2{\mathrm{C}}_3$
$6.0 \mathrm{g}$ of $\mathrm{A}$, $6.0\times {10}^{23}\mathrm{ }$ atoms of $\mathrm{B}$ and $0.036 \mathrm{mol}$ of $\mathrm{C}$ reacted and formed $4.8 \mathrm{g}$ of compound $\mathrm{A}{\mathrm{B}}_2{\mathrm{C}}_3$. If the atomic mass of $\mathrm{A}$  and $\mathrm{C}$ are $60$ and $80 \mathrm{amu}$, respectively. What is the atomic mass of $\mathrm{B}$ in $\mathrm{amu}$? (Avogadro number$=6\times {10}^{23}$)