One passenger (Mr Robinson) lives in Detroit, one lives in Chicago and the third (brakeman's neighbor who earns exactly 3 times as much as the brakeman) lives half way between those cities. Since Mr. Jones earns $80,000, an amount that isn't exactly divisible by 3, he can't be the one who lives between the cities. We were told that Mr. Robinson lives in Detroit. Therefore, Mr. Jones lives in Chicago. Accordingly, the brakeman, who has same name as the Chicago passenger, is Jones. If the brakeman is Jones, and Smith is not the fireman (Smith beats fireman at billiards), Smith must be the engineer.