Figure shows an isolated system.
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For isolated system, net charge is zero.
`2(x-20)+4x + (x + 10)2=0`
or `8x=20` or `x=2.5 V`
Thus, charge on capacitor `(1)` is `35 muC`
Thus, charge on capacitor `(2)` is `10 muC`
Thus, charge on capacitor `(3)` is`25 muC`.