Why did the classical macroeconomic school of thought lose its credibility during the 1930's?

Assume you work 40 hrs. per week at a wage rate of $40 per hour. Your employer offers you a choice: stay at 40 hrs. a week at $40 per hour or increase your productivity by working a 75 hour week (15 hrs. per day) at a pay rate of $100 per hour. Tell us about your decision and explain fully why this is your choice.