AAA Corporation is preparing a flexible budget and desires to separate its electricity expense, which is semi-variable and fluctuates with total machine hours, into its fixed and variable components. Information for the first three months of 2019 is as follows: Machine Hours Electricity Expense January 3,500 31,500 February 2,000 20,000 March 4,000 35,600 Requirements: 1. Compute the variable rate per machine hour. 2. Compute the fixed portion of Johnson's electricity expense. 3. Compute the total manufacturing costs if Johnson's actual machine hours are 4,500