Two capacitors A and B with capacities $C_1 and C_2$ are charged to potential difference of $V_1 and V_2,$respectively. The plates of the capacitors are connected as shown in the figure. The upper plate of C₁ is positive and that of C₂ is negative. An uncharged capacitor of capacitance C and falls on the free ends to complete circuit, then 

Charge on positive plate of A is $C_1{V}_1.$ Charge on negative plate of B is  $-C_2{V}_2.$ When d plate of capacitor C is connected with the plate of A, then the total charge of (d, a) plate system will be $C_1{V}_1$ (conservation of charge). 

$$\begin{gathered} \text{ Similarty on }(c,s)\text{ plates, total charge will be }-C_2{V}_2\text{.} \\ \text{The total charge on }(b,g)\text{ plate system will be }+C_2{V}_2-C_1{V}_1\text{. } \end{gathered}$$