Mutual aggreement to decode file I have a question about mutual agreement to decode a file

How could you choose to decode a file only if more than half the people present (let's say 6 out of 10 ) say Yes.

And there is only one key, in what form should the key be stored.
The obvious solution would be to use secret sharing: the file $F$ is encrypted using a secret key $K$, and $K$ is secretly shared between the $n$ parties, so that if at least $t$ parties reveal their share, the key $K$ can be reconstructed, while if less than $t$ parties reveal their share, the key $K$ remains perfectly hidden: Secret sharing can be constructed from simple interpolation methods, see Shamir's secret sharing scheme.

An issue of the above method is that, once the key $K$ is reconstructed, everyone knows it, so a fresh new key should be generated and shared between the parties for each file that we want to encode. A better solution, where many files can be encrypted using the same key, and so that a sufficiently large group of parties can decrypt a given file without leaking anything about the remaining encrypted files, is to use threshold encryption. A public-key threshold encryption scheme allows everyone to encrypt a file, but the decryption is performed as an interactive protocol between parties holding shares of the secret key. We know construction of such schemes from most standard cryptographic assumption, such as DDH.