Labour costs

Illustration Basic pay = $9/hour for a 40 hour week. Normal production in that time = 120 units Bonus = 50% of the time saved on production paid at time and a third What will be the total wage in a week in which 150 units are made in 40 hours? Answer: $ Basic pay = 40 x $9 360 150 units should take 50 hours 150 units did take 40 hours Hours saved 10 hours Bonus = 50% x 10 x 9 x 1 ? = 60 Total pay 420 I cant figure out how the bonus is 60 when 1 into one third is 0.33333?