Em tham khảo nha:
\(\begin{array}{l}
\overline {{M_{Ag}}} = 107 \times 51,84\% + 109 \times 48,16\% = 107,9632\,g/mol\\
{n_{Ag}} = \dfrac{{21,6}}{{107,9632}} = 0,2\,mol\\
{n_{^{107}Ag}} = 0,2 \times 51,84\% = 0,10368\,mol\\
{m_{^{107}Ag}} = 0,10368 \times 107 = 11,09376g
\end{array}\)