Problem
Johnny's Carpet cleaning service had revenues that averaged $70,000 per week in April and $60,000 per week in May. During both months, the company employed 6 full-time (40 hours/week) workers. In April the firm also had 4 part-time workers working 25 hours per week but in May there were only 3 part-time workers and they only worked 10 hours per week. What is the percentage change in labor productivity from April to May for Johnny's Carpet cleaning service?