You have to work the problem backwards from the way it was asked so Scott earns 48 which is 10 more than what mike earns so subtract 10 from 48. That equals 38 which is what mike earns. Mike earns 8 dollars more than what Jim earns so subtract 8 from 38 which equals 30. So Jim earns $30 a day. I hope explaining it out like this helped.
