private void AddToPayroll(PayStub payStub, List<PayStub> payroll)
        {

            var existing = payroll.Find(x => x.EmployeeId.Equals(payStub.EmployeeId));

            if (existing == null)
            {
                payroll.Add(payStub);
            } else
            {
                existing.HolidayHours += payStub.HolidayHours;
                existing.NormalHours += payStub.NormalHours;
                existing.Earnings += payStub.Earnings;
            }
        }
        private void CalculateEarnings(PayStub payStub)
        {
            var wage = payStub.Wage;

            payStub.NormalHours = Math.Round(payStub.NormalHours, 2);
            payStub.HolidayHours = Math.Round(payStub.HolidayHours, 2);

            var normalHours = payStub.NormalHours;

            if (normalHours > 40)
            {
                normalHours = (1.5 * (payStub.NormalHours - 40)) + 40;
            }

            var earnings = Convert.ToDecimal(normalHours + 2 * payStub.HolidayHours) * wage;
            payStub.Earnings = Math.Round(earnings, 2);
        }