The for whom tom works is Mr. Thomas.How has Mr. Thomas manipulated the bank?

I think your question should be more like "How is Mr. Thomas manipulated by the banks?" Mr. Thomas would like to pay his workers more than 25 cents a day. The banks, however, want to keep the workers' wages kept down. Mr. Thomas has to abide by the banks or else he won't get the loan he needs to keep his ranch working.