Advanced Physics $-$ Capacitor

Please kindly show me clear steps and explanation, thanks a lot!

Two metallic spheres are very far from each other. The $1$st has a capacitance C$1=8$pf and carries a charge Q$1=20$nC$.$ The second has a capacitance C$2=5$pF and carries a charge Q$2=40$nC$.$ We connect them with a very fine metal wire. Calculate:

a$)$ what potential V$*$ must they carry when they are connected, so that the chap on one of the two reaches the $<>$ field E$*=8$kv$/$cm$,$ which would cause an electric shock. In what sphere does it occur?