\({V_B}\,\, - \,\,{V_A}\,\, = \,\,\frac{{{q_1}}}{{{C_1}}}\,\, - \,\,\varepsilon \,\, + \;\,\frac{{{q_2}}}{{{C_2}}}\)
\(10\,\, = \,\,\frac{q}{1}\,\, - \,\,10\,\, + \;\,\frac{q}{2}\,\,\,\,\,\therefore \,\,\,\,\frac{3}{2}\,q\,\, = \,\,20\,\,\,\,\,\therefore \,\,\,\,q\,\, = \,\,\frac{{40}}{3}\,\,\mu C\)
$\left(\varepsilon_{0}=8.85 \times 10^{-12} C ^{2} N ^{-1} m ^{-2}\right)$