Because the employer did not keep adequate records to show how much of an employee’s pay was based on commissions, the trial court correctly divided the entire compensation received by the employee during the week by 40 to determine his base pay for calculating the 150% of base pay owed for overtime work. Had the employer kept better records, the amount paid as commission would have been divided by the employee’s actual hours worked during the week, not by 40. But as there was no way to tell what was commission and what wasn’t, the trial court did not err in dividing the entire weekly pay by 40 rather than actual time worked.