piece work rate

hello, can someone explain to me just how they arrived at the figure for the number of employees ? I couldn't find the figure in the question but it was provided in the answer. Thanks. A business currently uses a piecework scheme to pay its direct labour. Employees are paid $3.50 per unit for the first 50 units and $4.00 per unit for every unit above 50 produced in a week. On average an employee produces 60 units in a 38 hour working week. Management are considering changing to a per hour labour remuneration scheme, where employees would be paid a basic wage of $5.00 per hour for a 36 hour working week with overtime paid at a premium above basic wage of $2.40. There is not expected to be a change in the level of productivity. What is the change in unit labour cost from the piecework system to the proposed hourly rate system?