A coil has 600 turns which produces `5 xx 10^-3 Wb//turn` of flux when `3 A` current flows in the wire. This produced `6 xx 10^-3` Wb/turn in 1000 turns secondary coil. When the opened, the current drops to zero in `0.2 s` in primary. Find
(a) mutual inductance,
(b) the induced emf in the secondary,
(c) the self-inductance of the primary coil.