Two bank robbers, Ron and Jon, have managed to steal 42 crates
of gold and silver bars from a bank, 392 of the bars they stole being gold.
Among the 42 crates, there are two distinctive types.
One type of crate contains 11 bars and is worth $140k,
the other contains 20 bars and is worth $280k.
Jon was elected to calculate how the takings would be divided between them,
and decided that he would take all of the crates that contained 20 bars
and leave the rest to Ron.
Ron is unhappy that he's left the crates worth half as much Jon's.
Given that each gold bar is worth $15k and each silver bar is worth $10k,
work out how much Jon has given himself more than he has Ron?